^     THf      \ 
O   LIBRARIES   Z 


ITEALTE 


Digitized  by  the  Internet  Archive 

in  2010  with  funding  from 

Open  Knowledge  Commons 


http://www.archive.org/details/unitedstatesarmOOunit 


UNITED  STATES  ARMY 
X-RAY  MANUAL 


UNITED  STATES  ARMY 

X^RAY  MANUAL. 

r 

AUTHORIZED  BY  THE  SURGEON-GENERAL  OF  THE  ARMY 

Prepared  under  the  Direction  of  the 
Division  of  Roentgenology 


[219  illustrations] 


NEW  YORK 

PAUL  B.  HOEBER 

67  69  EAST  59TH  STREET 
I918 


Copyright,  1918 
ByPAULB.HOEBER 

Published,  October,  1918 


L\    \    O 


X)^.Cf< 


orVnc^YV_ 


.\ 


(_LO^ 


f 


I  u 


Printed  in  the  United  States  of  America 


CONTEXTS 


Introduction 

13 

1. 

X-Ray  Physics    . 

15 

2. 

Laboratory  Experiments 

133 

3. 

New  Apparatus 

149 

4. 

Standard  Positions    . 

188 

5. 

Dangers  and  Protection 

194 

6. 

Fluoroscopy 

202 

7. 

Localization 

209 

8. 

Bones  and  Joints 

292 

9. 

Sinuses  and  Mastoids 

346 

10. 

Teeth  and  Maxillae  , 

357 

11. 

Thoracic  Viscera 

369 

12. 

Urinary  Tract    . 

419 

13. 

Gastro-Intestinal  Tract 

434 

14. 

IMeasurement  of  X-Ray  Dose 

463 

15. 

Cutaneous  X-Ray  Therapy 

469 

16. 

Synoptical  Table  of  Contents 

.    487 

17. 

Index  .... 

.    493 

LIST  OF  ILLUSTRATIONS 

FIG.  PAGE 

22 
25 

26 
29 
33 
33 

34 
36 


1.  Generator  on  open  circuit  ...... 

2.  Simple  electric   circuit         ...... 

3.  Current-time  curve  of  a  simple  a.-e.  circuit 

4.  Regular  gas  containing  tube       ..... 

5.  Coolidge   cathode   construction     ..... 

6.  Coolidge   tube       ........ 

7.  Wiring  diagram  for  Coolidge  filament  transformer  . 

8.  Eadiator  type   of  Coolidge  tube  .... 

9.  Current    and    voltage    curve    for    self -rectifying    Coolidge 

tube  ......... 

10.  Variation  of  size  of  shadows  of  small  objects  with  a  wide 

focus   tube        ........ 

11.  Current-voltage  lines  of  Coolidge  tube  for  fixed  filament 

temperatures    ........ 

12.  Relation  between  kilovolts  and  spark  gap  . 

13.  Protection  from  surge  by  use  of  a  lamp     ... 

14.  Consumption  of  voltage  by  primary  of  x-ray  transformer 

and   series  resistance        ...... 

15.  Rheostat  construction  and  connections 

16.  Theoretical  chart  line  ...... 

17.  Wiring  diagram  of  autotransformer  .... 

18.  Relation  of  x-ray  production  on  rheostat  and  autotrans 

former    control         ....... 

19.  Partial   ''chart"   of   a   particular  machine  with  rheostat 

control      ......... 

20.  Partial  ' '  chart ' '  of  the  same  transformer  using  autotrans 

former   control  ....... 

21.  Wiring  of  ''polarity"  switch     ..... 

22.  Principle  of  polarity  indicator     ..... 

23.  Principle  of  rotary  converter       ..... 

24.  Relation  between  d.-c.  voltage  supplied  and  a.-c.  voltage 

delivered  ........ 

25.  Secondary  circuit  for  four  arm  rectifier 

26.  Secondary  circuit  for  two  arm  rectifier 

27.  Secondary  circuit  for  disc  type  of  rectifier 

28.  Relation    between    an    electric    current    and   its   resulting 

magnetic   field  ....... 

29.  Arrangement    for    constant    resistance    between    filament 

transformer  and  Coolidge  filament 

30.  The   path   of   negative    charge    from    line    through    spark 

gap,  tube  and  milliammeter    »         .         .         .         . 

7 


37 

39 

43 
46 

48 

50 
51 
53 
54 

56 


59 
60 
61 
62 

63 
65 
65 
66 


73 
74 


8  LIST  OF  ILLUSTRATIONS 

FIG.  PAGE 

31.  Simple  primary  circuit,  rheostat  control     ....       76 

32.  Addition   of  reversing  switch    (polarity  changer) 

33.  Magnetic   control-switch   added 

34.  Time      switch      added 

35.  Multiple  primary  taps  added 

36.  Autotransformer  instead  of  multiple  primary  taps     . 

37.  Fundamental  diagram  of  x-ray  machines  . 

38.  Use  of  a  lamp  in  trouble  hunting      .... 

39.  Softening    and    raising    connections    on    Snook    hydrogen 

tube 

40.  Storage   battery   charging    ...... 

41.  Emergency  rheostat  for  control  of  primary  of  x-ray  trans- 

former     ......... 

42.  Emergency  use  of  10  ampere  fuse  wire 

43.  Valve  tube 

44.  Vacuum  tube   oscilloscope   ...... 

45.  Operation  of  induction  coil  with  mercury  interrupter 

46.  Operation  of  induction  coil  with  electrolytic  interrupter 

47.  Centrifugal  jet  mercury  interrupter  .... 

48.  ''Eotax"    interrupter  .         .         .         . 

49.  Oscillogram — induction   coil   current  with   a   gas   mercury 

interrupter        ........ 

50.  Oscillograms — induction    coil    currents    with    Wehnelt    in- 

terrupter ........ 

51.  The  relation  between  exposure   and   density   of   a   photo- 

graphic plate  ........ 

52.  Finding  speed  factor  of  intensifying  screen 

53.  Viewing  box         ........ 

54.  Simple  arrangement  of  light  for  developing 

55.  A  convenient  darkroom  arrangement  .... 

56.  Wooden    developing    tank 

57.  Simple  ventilator  for  darkroom 

58.  Eecord  and  report  form  for  x-ray  examination  . 

59.  Diagram  of  connections  of  instruction  unit 

60.  Machine  used  for  instruction  purposes 

61.  Effect  of  scattering  on  undercutting  of  image  . 

62.  Standard  U.  S.  Army  x-ray  table  (Base  Hospital  type) 

63.  Standard  U.  S.  Army  x-ray  table   (Portable  unit  type) 

64.  Framework  of  standard  army  x-ray  table  and  operating 

pull  switch       ........ 

65.  Details  of  tube  box,  cradle  and  shutter 

66.  Mounting  of  standard  type  tube  in  army  x-ray  table 

67.  Tube  box  and  mount  for  radiator  type  tube 

68.  Screen-carrying    mechanism  ..... 

69.  Method  of  handling  screen  and  shutter 

70.  Measurement  target-screen  distance,  standard  screen   car- 

rier ......... 

71.  Method  of  centering  tube  in  box         .... 

72.  United  States  Army  portable  x-ray  unit  complete 


LIST  OF  ILLUSTRATIONS  9 

FIG.  PAGE 

73.  Wiring  diagram  for  United  States  Army  portable  x-ray 

unit 168 

74.  Instrument  box  for  portable  unit,  front  view     .         .         .172 

75.  Instrument    box   for    portable   unit    showing    instruments, 

high  tension  terminals,  and  openings  for  connections     .  174 

76.  Connections  for  red  lamp  over  the  fluoroscopic  table,  when 

used  with  portable  or  bedside  unit  .          .         .         .         .  177 

77.  United  States  Army  bedside  unit        .         .         .         .         .178 

78.  Position  of  parts  when  using  the  bedside  unit  for  chest 

examination  at  the  bedside     .         .         .         .         .         .180 

79.  Eotary  converter  used  for  d.-c.  operation  of  the  bedside 

unit 181 

80.  Wiring  diagram  of  connections,  United  States  Army  bed- 

side unit  for  110-220  volt  d.c.  or  110  volt  a.c.     '  .         .182 

81.  Wiring  diagram  of  connections  United  States  Army  bed- 

side unit  for  220  volts  a.c 183 

82.  Position  for  (a)  clavicle  (b)   shoulder  joint       .         .         .  188 

83.  Position  for  elbow,  lateral  view  ......  189 

84.  Position  for  elbow,  anteroposterior  view     ....  189 

85.  Position  for  wrist,  anteroposterior  view     ....  189 

86.  Position  for  wrist,  lateral  view 189 

87.  Position  for  hip  joint,  anteroposterior  view        .         .         .  190 

88.  Position  for  knee,  anteroposterior  view       ....  191 

89.  Position  for  knee,  lateral  view 191 

90.  Position  for  ankle,  anteroposterior  view     ....  191 

91.  Position  for  ankle,  lateral  view 191 

92.  Position  for  foot,  anteroposterior  view       ....  192 

93.  Position  for  foot,  lateral  view     ......  192 

94.  Position  for  posterior  portion  of  os  calcis  ....  192 

95.  Eesuscitation  from  electric  shock       .....  200 

96.  Dessane's  fluoroscope  attached  to  the  head  ready  for  ex- 

amination         .........  203 

97.  Dessane's  fluoroscope  elevated  to  the  top  of  the  head  after 

the  fluoroscopic  examination  ......  204 

98.  Method  of  distinguishing  between  skin  marks  and  denot- 

ing depth  of  foreign  body  from  skin  marker  .         .         .  211 

99.  Apparatus  for  Method  A 220 

100.  Principle  of  Metliod  A 221 

101.  Successive  appearances  on  fluoroscopic   screen  in  Metliod 

A 223 

102.  Euled  celluloid  sheet  to  indicate  equality  of  displacement 

of  two  shadows  in  Method  B 225 

103.  Parallax  localizer 226 

104.  Principle   of  parallax  metliod         .         .         .         ...  227 

105.  Apparatus  for  Method  B     ......         .  228 

106.  Principle  of  single  tube  shift  method         ....  231 

107.  Wall  meter  or  indicator  for  tube  shift  method  .                  .  232 

108.  Apparatus  for  Method  C     . 235 

109.  Use  of   double   slider  caliper  in   measuring  target-screen 

distance — Method  C 237 


10  LIST  OF  ILLUSTRATIONS 

FICJ.  PAGE 

110.  Principle  of  profondometer  strip         .         »         .         -         .     239 

111.  Hirtz   compass „     242 

112.  Schematic  drawing  of   Hirtz  compass  with  legs  adjusted 

at  zero  points  and  resting  on  a  plane     ....     24:3 

113.  Arms  and  indicator  of  Hirtz  compass,  same  position  but 

with  legs  elevated  on  blocks  ......     244 

114.  Schematic   drawing  of   Hirtz   compass  set  up  on  skin   of 

patient 245 

115.  Hirtz  compass  in  position  .         .         .         o         ,         .         .  246 

116.  Eeason  for  shift  of  leg  of  compass  from  zero  point         .  247 

117.  Accessory    apparatus    for    fluoroscopic    work    with    Hirtz 

compass    ..........     248 

118.  Method  of  using  fluoroscopic  adapter  wdth  Hirtz  compass.     251 

119.  Setting   arms   and   legs   of    Hirtz    compass    directly    from 

fluoroscopic   adapter         .......     253 

120.  Detail  of  holder  for  direct  setting  of  Hirtz  compass  .         .     255 

121.  Direct  setting  of  Hirtz  compass.     Compass  and  holder  in 

position 257 

122.  Centering   of   tube   above   plate   holder   on   cassette   with 

small  cross  wires,  photographic  method,  Hirtz  compass     259 

123.  Skin   markers,  plate  holder  and  tube   holder  in  position 

for  photographic  method,  Hirtz  compass       .         .         .     260 

124.  Schematic  representation  of  plate,  cross  wire  marker  and 

tube  focus  positions  for  radiographic  use  of  Hirtz  com- 
pass   262 

125.  Construction  for  finding  foot  points 262 

126.  Complete  chart  for  setting  feet  of  Hirtz  compass      .         .  264 

127.  Equipment  supplied  for  use  with  Hirtz  compass         .         .  267 

128.  Apparatus  for  Method  F 268 

129.  Use  of  MetJiod  F  with  a  perforated  screen  ....  269 

130.  Set    of    localization    accessories    supplied    in    the   regular 

army    outfit       .........     271 

131.  Intermittent    control.     Eoentgenologist    w-ith    fluoroscope, 

raised  ready  to  lower  it  and  proceed  with  examination  .     273 

132.  Intermittent  control.     Surgeon  and  roentgenologist  work- 

ing simultaneously  ........  273 

133.  Head  rest  for  use  with  the  eye  localizer      ....  279 

134.  Sweet  eye  localizer       ........  280 

135.  Position  for  first  exposure  in  localization  of  projectiles  in 

the  eye     ..........     283 

136.  specimen  plate  of  projectile  in  the   eye  illustrating  the 

method  of  measurement  .......     284 

137.  Second  exposure  for  localization  of  projectiles  in  the  eye  .     285 

138.  Schematic    drawing    of    localizing    chart    illustrating    the 

method  of  obtaining  measurements         ....  286 

139.  Chart  used  in  eye  localization     ......  287 

140.  Position  for  examination  of  frontal  region  of  skull  .         .  307 

141.  Position    for    examination    of    temporoparietal    region    of 

skull 308 


LIST  OF  ILLUSTRATIONS  11 

FIG.  PAGE 

142.  Position  for  examination  of  posterior    (occipital)    region 

of    skull 309 

143.  Position  for  examination  of  basilar  region  of  skull    .         .  311 

144.  Positions  for  examination  of  spine     .....  314 

145.  Spine  examination,  anteroposterior  position  for  upper  cer- 

vical vertebra'  .........  316 

146.  Spine  examination,  anteroposterior  position  for  lower  cer- 

vical   vertebra?  .         .         .         .         .         .         .         .317 

147.  Spine  examination,  lateral  position  for  examination  of  cer- 

vical  vertebnie      ........  317 

148.  Spine  examination,   anteroposterior   position   for   thoracic 

vertebra?            .........  318 

149.  Spine    examination,   position   for   lateral   examination    of 

thoracic    vertebrae    .         .         .         .         .         .         .         .319 

150.  Spine    examination,    anteroposterior    position    for    upper 

lumbar      region       .         .         .         .         .         .         .         .319 

151.  Spine  examination,  lateral  position  for  lumbar  vertebrae  .  321 

152.  Spine    examination,    anteroposterior    position    for    lower 

lumbar   vertebrae      .         .         .         .         .         .         .         .321 

153  and  154.     Position  for  mastoid  examination  ....  347 

155.  Schematic  drawing  illustrating  correct  angle  for  postero- 

anterior  accessory  sinus  examination       ....  349 

156.  Position    for    postero-anterior    examination    of    accessory 

sinuses      ..........  350 

157    and    158.     Position   for   lateral    examination    of    accessory 

sinuses 351 

159.  Position  for  examination  of  sphenoid  sinus       .         .         .  353 

160.  Position  of  patient,  film  and  tube  for  exposure  of  upper 

molar   region    .         .         .         .         .         .         .         .         .358 

161.  Adjustment  for  exposure  of  upper  bicuspids,  canine  and 

lateral   incisor           .........  358 

162.  Adjustment  for  exposure  of  lower  molars  ....  359 

163.  Adjustment    for    exposing    "ower    bicuspids,    canine,    and 

lateral   incisor          .         . 359 

164.  Normal  teeth  except  for  unerupted  canine  .         .         .         .  360 

165.  Localized  areas  of  destruction  of  alveolar  margin     .         .  361 

166.  Sarcoma  of  mandible  ........  362 

167.  Acute   abscess 362 

168     Multiple   chronic   abscesses  .......  363 

169.  Advanced  pyorrhoea 364 

170.  Abscesses,  involving  unerupted  teeth           ....  366 

171.  Adjustment   for    exposure   of    anterior   portion    of   upper 

jaw           ..........  366 

172.  Adjustment  for  exposure  of  anterior  portion  of  mandible  367 

173.  Adjustment  for  exposure  of  posterior  two-thirds  of  man- 

dible, the  articulation  of  the  jaw,  and  the  zygoma         .  367 

174.  Adjustment  for  exposure  of  upper  jaw       .         .         .         .  368 

175.  First  oblique  position  for  chest  ......  370 

176.  Second  oblique  position       .......  370 

177.  Third  oblique  position 371 


12 


LIST  OF  ILLUSTRATIONS 


FIG. 

178.  Fourth     oblique     position  .... 

179.  Dorsoventral    (postero-anterior)   position  for  chest 

180.  Lateral  recumbent  position  for  chest 

181.  Normal   heart    (orthodiagram) 

182.  Mitral    insufJficiency 

183.  Pure  mitral  stenosis     . 

184.  Aortic   insufficiency 

185.  Atheroma  of  the  aorta 

186.  Drop   heart  .... 

187.  Large  pericardial  effusion  . 

188.  Chest  plate  made  for  examination  of  the  heart 

189.  Type  of  tracing  furnished  clinician  with  report 

190.  Planimeter 

191.  Examination  of  upper  half  of  urinary  tract 

192.  Position  for  upper  half  of  urinary  tract     . 

193.  Position  for  lower  half  of  urinary  tract 

194.  Position  for  bladder  and  prostate 

195.  General  view"  of  patient  on  table 

196.  Diverticulum  of   esophagus 

197.  Benign  stricture  of  esophagus     . 

198.  Carcinoma  of  esophagus  at  level  of  bifurcation  of  trachea 

199.  Cardiospasm;  note  marked  dilatation  of  esophagu 

200.  Penetrating  ulcer  on  lesser  curvature  of  stomach 

201.  Excavating  ulcer  of  lesser  curvature 

202.  Marked  dilatation  of  stomach  due  to  obstruction  at  py- 

lorus ........ 

203.  Large  carcinoma  of  stomach      .... 

204.  Carcinoma  of  stomach,  moderate  size 

205.  Duodenal  ulcer,  showing  defect  in  duodenal  bulb 

206.  Mucous  colitis  shown  by  stringy  shadow  of  the  barium 

207.  Diverticulitis   of   colon 

208.  Carcinoma  of  ascending  colon     . 

209.  Carcinoma  of  hepatic  flexure 

210.  Carcinoma  of  cecum   .... 

211.  Dyschezia;  note  dilatation  of  rectum 

212.  Angulation  at  duodenojejunal  junction 

213.  Appendix      ...... 

214.  Incompetency  of  ileocecal  valve  . 
215  Gall-stones    ...... 

216.  Dosage  curve  for  various  spark  gaps  . 

217  and  218.     Five  areas  and  angles  of  incidence  of  rays 

219.  After  depilation  by  Adamson  method 


INTRODUCTION 

THIS  manual  has  been  prepared  under  the  direction  of 
the  Surgeon  General  of  the  Army  to  serve  as  a  guide 
to  roentgenologists  who  are  doing  the  x-ray  work  in  our 
military  hospitals,  and  as  a  textbook  for  instruction  in  mili- 
tary roentgenology.  It  will  supersede  the  small  U.  S. 
Army  X-Ray  Manual  which  was  hurriedly  prepared  at 
the  beginning  of  the  war  to  facilitate  the  instruction  of 
the  many  inexperienced  men  who,  of  necessity,  had  to  be 
trained  to  do  x-ray  work. 

The  manual  is  not  intended  to  be  a  complete  treatise 
on  roentgenology,  but  in  the  portion  devoted  to  x-ray  diag- 
nosis the  aim  has  been  to  state  as  concisely  and  clearly 
as  possible  the  facts  that  have  been  established  by  ex- 
perience, and  to  avoid  all  controversial  points. 

There  is,  of  course,  no  clear  line  of  demarcation  between 
military  roentgenology  and  roentgenology^  of  civil  practice. 
It  is  the  same  art,  but  practiced  under  different  circum- 
stances and,  sometimes,  with  an  entirely  different  type  of 
apparatus.  The  principal  aim  in  the  preparation  of  this 
manual  and  in  the  courses  of  instruction  carried  on  by  the 
Medical  Department  has  been  to  familiarize  the  already 
experienced  roentgenologist  with  the  apparatus  with  which 
he  is  to  work,  and  to  give  him  additional  instruction  along 
any  lines  in  which  he  may  be  deficient.  The  need  for 
a  large  number  of  roentgenologists,  however,  has  rendered 
it  necessary  to  train  for  this  work  physicians  who  have 
had  little  or  no  previous  experience  and,  for  this  reason, 
it  has  been  necessary  to  cover  in  the  manual  practically 
all  phases   of  roentgenology. 

13 


14  INTRODUCTION 

The  parts  of  the  manual  devoted  to  the  localization  of 
foreign  bodies  and  to  a  description  of  new  apparatus 
deserve  special  attention.  The  localization  of  foreign  bodies 
occupies  most  of  the  roentgenologist's  time  in  the  forward 
hospitals,  and  he  must  thoroughly  master  the  methods 
described.  The  new  apparatus  described  in  Chapter 
III  has  been  developed  either  just  preceding  or  subse- 
quent to  the  entry  of  our  country  into  the  war.  It  differs 
in  many  respects  from  the  apparatus  in  use  in  civil  hos- 
pitals. Some  of  this  new  apparatus,  such  as  the  port- 
able and  the  bedside  unit,  have  certain  limitations.  These 
must  be  recognized  and  must  not  be  exceeded.  It  should 
not  be  concluded,  however,  that  because  there  are  certain 
limitations  the  apparatus  is  of  little  value.  For  instance, 
the  maximum  current  to  be  obtained  from  the  bedside  ap- 
paratus is  five  milliamperes,  but  this  low  milliamperage 
is  rendered  very  effective  by  the  constant  and  properly 
selected  voltage  and  the  quality  of  the  plates  resulting 
from  the  fine  focus  of  the  special  type  of  Coolidge  tube 
employed.  For  bedside  work  in  many  of  our  large  hospi- 
tals this  apparatus  has  been   found  invaluable. 

The  great  importance  of  the  x-ray  in  military  surgery 
and  medicine  has  been  established  so  that  the  roentgenolo- 
gist has  a  position  of  much  responsibility.  He  must  re- 
member, however,  that  his  work  is  valuable  only  in  so  far 
as  he  assists  the  physician  or  surgeon  in  arriving  at  cor- 
rect conclusions,  and  that  this  can  be  accomplished  only  by 
mutual  cooperation.  The  roentgenologist  does  his  part 
by  presenting  to  the  surgeon  accurate  findings  carefully 
recorded  in  a  usable  form.  After  he  gains  the  confidence 
of  the  surgeon  in  the  accuracy  of  his  work  and  the  sound- 
ness of  his  judgment,  the  exercise  of  a  little  tact  will 
alwaj^s  make  it  possible  for  him  to  secure  full  cooperation 
and  thus  give  to  the  x-ray  examination  its  maximum  value. 


UNITED  STATES  ARMY 
X-RAY  MANUAL 


X-RAY    PHYSICS 

Introduction. — The  following  brief  notes  on  the  phys- 
ical aspects  of  the  apparatus  likely  to  be  used  in  military 
roentgenology  have  been  written  with  the  hope  that  their 
study  might  enable  the  roentgenologist  to  prepare  for 
service  in  less  time  and  be  better  able  to  utilize  the  appara- 
tus with  which  he  is  compelled  to  work.  AYith  the  belief 
that  brief  reasons  as  to  why  things  are  done  are  good 
guides  in  operation,  rather  more  explanation  of  fundamen- 
tal principles  has  been  given  than  is  usually  included. 

X-Rays. — The  roentgen  or  x-rays  are  produced  by  an 
electric  current  in  a  glass-walled  vacuum  tube.  Such  a^ 
current  is  due  to  the  projection  of  minute  electric  particles 
(electrons)  from  one  metal  terminal,  the  cathode,  to  an- 
other metal  terminal,  the  anode  or  target.  The  x-rays 
originate  at  the  point  of  impact  of  the  electrons  on  the 
target  and  travel  out  fromtheir  origin  in  all  directions 
exi^t  where,  dense  material  obstructs  or  prevents  thei£ 
passage.  When  passing  through  bodies  made  up  of  various 
parts  differing  in  density,  some  of  the  rays  that  enter 
the  denser  portions  are  permanently  cut  out  and  a  new 
distribution  of  intensity  in  the  beam  results. 

The  presence  of  x-rays  must  be  determined  by  some  of 
^^     ^ 


16  U.  S.  ARMY  X-RAY  MANUAL 

the  effects  they  produce  when  acting  on^material  bodies. 
These  actions  are : 

1.  Effect  on  the  emulsion  of  a  photographic  plate. 

2.  Excitation  of  light  in  certain  crystals  (fluorescence). 


3.  Rendering  gases  conducting  to  electricity    (ioniza- 
tion). 

4.  Stimulating   or   destructive    action   on   living   cells 
(biological  action).  ^ 
Ti^  first,  second,  and  fourth  of  these  are  of  fundamental 
value  in  the  medical  and  surgical^  uses  of  the  rays.     The 

,  -  third  has  been  very  useful  in  the  study  of  the  radiation. 

^  ■^^<<^^^\iese  rays  do  not  excite  vision  on  reaching  the  retina 

\of  the  eye,  but  are  capable  of  originating  light  in  cer- 

A   uniform  beam,  falling  on  a  piece  of 

covered  with  such  crystals,  would  cause  uni- 

rr^^    -^form  illumination.     If  regions  of_unequal  material  den- 

L^..J'     sity^^have_ been  traversed   by  the  beam  before   reaching 

'***'***^'^he^screen    (fluproscope),  such  dense  portions  will  show 

as  areas  of  lesser  brightness  or^^  as  we  say,  will  cast  shad- . 

ow^   Injbhe  same  way,  a  photographic  plate  or  film  suffi^ 

ciently  acted  upon  by  such  rays  will,  on  development^give 

areas  of  unequal  blackening,  marking  out  the  projections^ 

of  volumesin^e  body  whose  densities  differ  from  those__^ 

''^^l^j^;- surrounding  them.    On  the  flio^roscopic  screen7dense  bodies 

•^  '/  -^shQw  as  dark  areas;  in  a  photographic  negHive,  they  show 

i^^  />-*uUc<It  has  been  shown  by  various  investigations  that  x-ra^^s 
^^^jif^  arejdentical  in  their  nature  with  light  and  electric  waves^ 
^&H.  except  that  their  wave  lengths  are  very  much  less__than 
I  \*y^*^  even  the  shortest  light  waves.  On  account  of  this  ex- 
'^^4%e^tremely  short  wavelength,  the  effec^  of  matter  uponjtheir 
jLi;S^|[J^!rop4gation  is  quite  different  from  that^n  the^ase^of_ 
longer  waves.  SuclSrshort  waves  are  only  produced  by  a 
change  in  the  velocity  of  electrons  taking  place  in  intervals 


':Jiy 


X-RAY  PHYSICS  17 

of  time   too   short  to  be   easily  conceited.     The  gamma 

rays  of  radium,  etc.,  are  simply  ravs  due  to  the  sudden  Z!^iC'^^ 

startmg  out  of  electrons  by  atomic^breakdo^vn.    They  may  ' 

be  shorter  or  longer  Hian  the  x-rays  we  use  m  fluoroscopy 

or  in  radiography. 

The  term  ray  is  used  to  designate  two  distinct  types 
of  phenomena.  One,  a  projectionof  small  particles_b^y 
_atomic  disintegration,  as Jbeta_ajid_al£haray^  The  other 
refers  to  the  transfer  of  physical  e^cts  by  the  agency  of 
wave  motion.  In  this  class  we  have  light,  gamma  and 
x-rays. 

It  may  be  also  noted  here  that  gamma  rays  are  of  the 
saffL£^h}"sical  nature  as  ^-rays,  but  some  gamma  ra^^s  are 
of  shorter  wave  length  than  the  x-rays  we  are  able  to  pro- 
duce a^he  present  time. 

The  following  general  propertiesof  this  radiation  should 
beunderstood  in  order  tg^facilitate  its  intelligent  applica- 
tion. '   ^ 

±*aths. — These  ra^y^Jrayel  in  straight  lines  into,  through,  ^  »>-*^^  i 
and^out  of  material  bodies,  except  where  the  atoms  them- rci^.  > 
selves  cause__scattering.  They  cayinot  be  directed  by  mir- 
rors  or  lenses  for  purposes  of  optical  focus  or^  concentra- 
tion, as  is  done  with  light.  The  slight  amount  of  regular 
reflection  by  the  uniformly  spaced  atoms  in  crystals  is 
too  smalPto  be  of  any  importance  to  the  roentgenologist. 

Velocity. — The  rays  travel  out  from  the  target  at  the 
same  velocity  as  light  or  electric  waves. 

Energy. — The  actual  energy  involved  in  an  x-ray  beam 
is  small  compared  with  that  expended  in  getting  it  started ; 
only  a  few  parts  in  a  thousand  of  the  energy  supplied 
is  converted  into  x-rays. 

Scattering. — X^^ra^  are  scattered  in  pas,sing_through 
matter  exactly  as  light  is  scattered  in  turbid  water,  fog, 


18  U.  S.  ARMY  X-RAY  MANUAL 

paraffin,  etc.  Only  a  part  of  a  beam  is  thus  scattered, 
the  remainder  passing  straight  through  or  being  absorbed. 
Scattering  confuses  shadows  on  screen  or  plate  in  a  very 
troublesome  way. 

Passage  Through  Matter. — When  rays  pass  through  ma- 
terial,  the  substance  is  called  transparent  to  the  radia- 
tion. If^little  or  no  radiation  gets  jthrough,  we  say  the 
material  is  opaque_to  this  radiation.  The  terms  transpar- 
ent and  opaque_refer  to  the  action  of  the  material  with 
reference  to  a  specific  type  of  radiation.  If  one  arranges 
a  YSLviety  of  substances  of  like  thickness  in  the  order  of 
increasing  density,  their  opacity  to  x-rays  will  be  nearly 
in  the  same  order.  But  this  will  vary  somewhat  according 
to  the  quality  of  the  x-ray  beam  considered.  That  portion 
of  the  incident  radiation  neither  transmitted  nor  scat- 
tered is  changed  into  heat  or,  as  we  say,  absorbed  in  the 
material.  We  then  say  that  absorbing  power  increases 
with  the  density  of  the  absorber.  This  absorbing  power 
is  best  expressed  as  the  fraction  of  the  rays  absorbed  by 
a  definite  thickness  of  material.  Thus,  if  1  cm.  of  water 
should  reduce  a  particular  radiation  so  that  the  emerging 
beam  is  half  as  effective  as  the  entering  one,  we  might 
say  this  radiation  has  a  half  value  layer  of  1  cm.  of 
water.  Two  centimeters  of  water  would  transmit  only  25 
per  cent  of  the  incident  beam  or  that  reaching  the  surface 
proximal  to  the  tube. 


it 

f^i/YjU^  The  quality  of  short  wave  length  and  high  penetration 

i^J^j'can  be  secured  only  by  means  of  high  voltage  operation. 

/'^'V,    (See  penetration,  p.  46.) 

i  h  ^      Electrons. — The  modern  concept  of  atoms  involves  the 

Hr  €»^*^  idea  of  their  general   electrical  constitution.     From  any 

^^j^a^'^dXQTii  there  may  be  abstracted  one  or  more  small  negative 

i^>wt.i2i^harges,  all  precisely  alike,  whose  properties  are  in  -no  wise 


X-RAY  PHYSICS  19 

dependent  on  the  atom  froin  which  they  conie,^nd  all  are. 
quite  capable  of  existence  by  themselves  without  jthe  pres- 
ence oT  the  remainder  of  the  atom.  These  little  bodies  have 
been  variously  named  as  corpuscles,  cathode  ra^^s,  beta 
rays,  electric-ions,  etc.  The  common  designation  of  elec- 
tron is  derived  from  the  latter.  An  electron  is  able  to 
respond  to  electric  force  and  to  acquire  velocity  under  such 
force  action.  When  in  motion,  they  show  all  the  charac- 
teristics  of  an  electric  current. 

The  main  physical^features  of  electrons^  arej_ 

1.  Their__fixed  and_definite_^egativ^  charge. 

2.  Their  extremely  small  mass  and  volume. 

3.  The   extreme   speed   they   may   acquire. 

Production  of  X-Rays. — Roentgen  or  x-rays  originate  in 
any  region  where  the  velocity  of  electrons  is  suddenly 
changed.  In  the  radio-active  breakdown  of  atoms,  this 
change  is  a  sudden  acquisition  of  velocity,  and  the  gam- 
ma rays  are  produced.  In  x-ray  tubes,  the  high-speed 
electron  is  stopped  in  its  flight  by  the  interposition  of  a 
target  metal  of  high  atomic  Aveight  placed  in  its  path,  and 
x-rays  result  from  a  loss  of  velocity. 

The  problem  of  x-ray  production  for  our  purpose,  then, 
resolves  itselT  into   four  parts._ 

1.  The  separation  of  electrons  from  atoms. 

2.  Giving  them  high  speed. 

3.  Concentrating  them  on  a  small  area. 

4.  Stopping  them  with  sufficient  suddenness. 

The  first  of  these  is  accomplished  in  one  of  two  ways. 
In  the  tubes  containing  a  small  amou7it__  ot^as,  electrons 
are  secured  in  pail^bg-  high  electric  field,  but  to  a  much 
grgeater  extent  bv  the  disruption  of  atoms  due^  to  the  mov- 
ing  electrons  and  by  the  x-rays  themselves.     In  the  more 


20  TJ.  S.  ARMY  X-RAY  MANUAL 

^^<£^.  recent  hot  cathode  tube  (C^olidge),  electrons  are  set  free 
*  ii^^^yy^f rom  the  atoms  in  a  tungsten  wire  by  the  action  of  heat. 
iii*i«^^In  the  former,  the  number  of  available  electrons  is  rather 
'■^^L  ^hard  to  control,  while  in  the  hot  cathode  tube  this  offers 


^ou/tuiJ^  difficulty. 


In  o^r^£^to  secure  high  speed_  (one-half  to  one-thiji^ 
the  velocity  of  light)  a  high  voltagemust  be  available, 
ana  -fclTe  electrons  must  all  be  urged  toward  the  same  small 
area  in  order  to  get  sharp  shadows7"""The^  concent^atTon 
on  the  target  is  secured  by  proper  design  of  the  elec- 
trodes and  their^  proper  position  in  the  tube.  In  all  cases 
the  path  to_^be^  followed  must  be  quite  freeof  gas  in 
order  to  avoid  obstruction.  " 

The  choice  of  metal  as  a  barrier  is  of  great  importance, 
and  only  a  few  elements  satisfy  the  conditions.  Every 
fast-moving  electron  has  some  mechanical  energy  and  this 
goes  mainly  into  heat  by  impact;  there  results  a^reat 
rise  in  temperature  at  the  _point  of  electron  concentration. 
As  radiographs  and  fluoroscopic  images  arepurely  shadow 
effects,^a  source  of  radiation  sfartingjrom  a  point  is  very 
desirable^.  This  high  concentration  of  heat  will  melt  any 
target  material  at  high  power  operation.  Only  metals  of 
high  melting  points  can  be  utilized,  such  as  platinum, 
tungsten,  osmium,  and  iridium.  Of  these  the  first  two  are 
in  common  use,  the  tungsten  to  a  great  extent  during 
recentyears.  Hi^  atomic  weight  is  also  desirable,  and 
fortunately  this  goes  with  high  melting  points  in  the  a^oye 
metals. 

General  Instructions  and  Precautions. — 1.  Excessive  ex- 
posure to  x-rays  results  in  serious  injury  to  the  skin. 
Such  injury  does  not  manifest  itself  at  once  but  may 
develop  some  weeks  later.  To  a  degree,  the  action  is 
cumulative,  so  that  a  single  dose,  in  itself  too  small  for 


X-RAY  PHYSICS  21 

injury,  may,  when  frequently  repeated,  be  harmful.  Read 
carefully  the  notes  as  to  protection,  page  19i.  AVhile 
it  is  unwise  to  be  over  timid,  it  is  much  easier  to  prevent 
an  injury  than  to  cure  it. 

2.  X-ray  apparatus  is  expensive,  and  not  only  is  it 
costly  in  money  to  repair  damage,  but  even  more  impor- 
tant is  loss  of  service  from  breakdown.  Do  not  try  to 
see  how  much  current  you  can  pass  through  a  tube  or 
how  long  a  spark  the  transformer  will  give.  Do  not 
imagine  that  a  tungsten  target  cannot  be  melted  j  it  can, 
and  very  quickly. 

3.  Acquire  the  habit  of  observing  whether  high  ten- 
sion wires  are  sufficiently  far  from  patient,  assistants, 
etc.,  before  you  close  the  operating  switch. 

4.  Make  all  tests  of  tubes,  etc.,  on  low  power,  when 
possible,  and  do  not  make  unnecessary  speed  your  ambi- 
tion. AYhen  through  work,  throw  all  controls  to  low 
power. 

5.  Never  test  out  a  tube  when  the  patient  is  in  posi- 
tion. 

6.  Always  see  that  current  is  passing  through  the  fila- 
ment of  a  Coolidge  tube  before  closing  the  main  trans- 
former switch. 

7.  Do  not  imagine  you  can  make  plates  of  thick  parts 
on  very  low  spark  gaps.  It  cannot  be  done,  but  you 
may  get  some  very  unfortunate  experience  trying  it. 

8.  Remember  that  any  current  that  passes  across  the 
spark  gap  or  leaks  from  one  line  to  the  other  along  walls, 
etc.,  does  not  help  to  produce  x-rays,  although  it  may  in- 
crease your  milliammeter  reading. 

9.  Try  to  develop  a  definite  order  and  sequence  in 
the  various  details  of  any  examination.  It  will  save  time 
and  prevent  errors. 


22 


U.  S.  ARMY  X-RAY  MANUAL 


10.  The  only  safe  time  to  label  a  plate  or  film  for 
identification   is   at  the  time   of  exposure. 

11.  Don't  imagine  that  so  and  so's  good  plates  are 
due  to  the  particular  machine  he  is  using;  and  don't 
chase  off  after  every  new  exposure  ''technique"  you  hear 
about.  The  fact  that  some  individuals  advocate  one  after 
another  is   ample   evidence  of  their  uselessness. 

Electrical  Terms. — Certain  terms  are  used  so  frequently 
in  all  discussion  of  electrical  matters  that  they  are  intro- 
duced at  this  point  for  convenience  in  reference. 

Charges. —  AVhen  any  physi- 
cal or  chemical  action  breaks 
down  the  connection  between  an 
electron  and  the  remainder  of 
the  atom,  the  electron  consti- 
tutes the  elementary  particle  of 
negative  electricity.  All  nega- 
tive charges  are  simply  countless 
numbers  of  electrons  kept  awav 
from  the  positive  portions  of  the 
atoms  from  which  they  were 
separated. 

Generators. — Generators  do 
not  create  electricity.  They 
take  electrons  and  positive  ato- 
mic remainders  apart  and  push  them  in  opposite  directions 
against  their  natural  tendency  to  keep  and  come  together. 
Thus,  if  G,  Fig.  1,  represents  a  generator,  A  and  B  metal- 
lic plates  connected  to  its  terminals,  A  is  covered  with  elec- 
trons and  B  with  enough  positive  to  neutralize  the  negative 
on  A,  If  we  call  e  the  negative  charge  of  one  electron,  and 
Q  the  total  charge  on  A,  N  the  number  of  electrons,  then  Q 
equals  Ne,  where  N  is  an  incredibly  large  number  in 
most  cases. 


Fig.  1.     Generator  on  open 
circuit. 


X-RAY  PHYSICS  23 

Voltage. — Electric  charges  separated  as  shown  in  Fig. 
1,  show:  (1)  a  mechanical  pull  on  the  bodies  A  and  B, 
(2)  a  decided  tendency  to  pass  between  A  and  B. 

A  voltmeter  does  not  measure  electricity  but  something 
like  a  pressure  or  strain  trying  to  pass  a  charge  between 
two  regions. 

The  Volt. — The  volt  is  the  unit  in  which  the  tendency 
of  charge  to  move  from  one  place  to  another  is  measured. 
The  electrical  tension  between  the  terminals  of  a  special 
cell  (Weston  or  Cadmium  cell)  is  taken  by  legal  definition 
as  1.019  volts. 

Current. — AYhen  proper  external  connections  are  made 
to  the  terminals  of  a  generator  there  results  a  transfer 
of  charge.  If  we  could  coiint  the  number  of  electrons 
passing  on  to  A  per  second,  say  n,  we  would  call  7ie  the 
current  passing  through  G.  An  electric  current  may  then 
be  regarded  as  a  measure  of  the  number  of  electrons  pass- 
ing per  second.  It  must  be  observed  that  after  A  and  B 
are  charged  as  highly  as  is  possible  for  the  particular  gen- 
erator, there  will  be  no  further  current,  but  the  voltage 
is  present.  We  may  have  voltage  existing  and  no  current, 
hut  never  a  current  without  some  voltage. 

The  Ampere. — The  ampere  is  the  unit  of  electric  cur- 
rent. It  is  legally  defined  as  the  rate  of  transfer  of  electric 
charge  which  deposits  silver  from  a  special  solution  at 
the  rate  of  .001118  grams  per  second.  The  unit  electric 
charge  is  the  coulomb.  Five  amperes,  for  example,  will 
transfer  40  coulombs  in  8  seconds. 

Resistance. — It  requires  but  little  voltage  to  move  a 
big  supply  of  electrons  through  some  materials,  while  with 
others  a  very  great  voltage  will  cause  but  little  electron 
movement.  The  former  are  named  conductors;  the  latter, 
insulators.     Note  carefully  that  the  difference  is  one  of 


24  U.  S.  ARMY  X-RAY  IMANUAL 

degree,  and  that  perfect  insulators  do  not  exist  so  far  as 
high  applied  voltage  is  concerned.  Thus,  dry,  clean  glass 
may  be  considered  an  insulator  for  moderate  voltages, 
but  may  conduct  to  a  considerable  extent  at  high  voltage. 
The  objection  offered  to  the  passage  of  an  electric  current 
by  any  material  included  in  a  circuit  is  called  its  resist- 
ance. 

The  Ohm. — The  unit  of  electrical  resistance.  Legally 
defined  as  the  resistance  of  a  uniform  column  of  mercury 
106.3  cm.  long  and  one  square  millimeter  section  at  0° 
centigrade. 

Power. — The  ability  of  the  electric  current  to  do  work 
is  termed  its  power. 

The  Watt. — The  watt  is  the  unit  of  electrical  power. 
It  is  the  power  of  a  current  of  1  ampere  in  a  region  where 
it  loses  1  volt.  The  product,  amperes  x  volts  lost  =  power 
in  watts ;  746  watts  are  equivalent  to  one  mechanical  horse- 
power, and  1  kilowatt  is  therefore  equal  to  about  1%  horse- 
power. 

Derived  Units. — The  units  given  above  are  not  of  con- 
venient size  in  all  cases,  and  some  modifications  are  in 
common  use.  The  terminal  voltage  on  the  tube  is  high, 
and  it  is  often  expressed  in  kilovolts  (1  kilo  volt  equals 
1000  volts).  The  current  ordinarily  used  through  x-ray 
tubes  is  small  and  is  expressed  in  milliamperes  (1  milli- 
ampere  equals  y^^  ampere).  The  power  used  to  oper- 
ate electrical  devices  is  generally  expressed  in  kilowatts, 
when  the  number  of  watts  is  large  (1  kilowatt  equals 
1000  watts).  One  kilowatt  maintained  for  one  hour  is 
named  a  kilowatt-hour. 

As  applied  in  particular  cases,  a  4  kw,,  110  volt  gen- 
erator, is  a  machine  that  delivers  4000  watts  at  full  load 
and  is  designed  to  operate  at  110  volts.     The  full  load 


"T^Jt       ^  X-RAY  PHYSICS  25 

current  would  be  ^^^-^  =  36.3  amperes.  If  a  machine 
gives  50  milliamperes  at  70  kilovolts,  the  power  delivered 
is  ^Aa^  X  70  X  1000 -=  3500  watts,  or  31/^  kw. 

Measuring  Instruments. — The  electrical  measuring  in- 
struments that  may  concern  the  roentgenologist  are  the 
ammeter  and  the  voltmeter  for  low  tension  circuits,  the 
milliammeter,  and  the  kilovoltmeter  for  high  tension  cir- 
cuits. Most  kilovoltmeters  are  of  little  real  value  as  they  vary 
with  the  secondary  current.  The  milliammeter  is  a  most 
valuable  aid  to  the  work.     It  is  often  designed  for  two 

iq  Ohms    Q 

— ^/\A/\/\/v^^^ 


Fig.  2.     Simple  electric  circuit. 

ranges.  From  0  to  15  ma.  on  one  scale  and  0  to  150  ma. 
on  the  other  is  the  best  for  most  work. 

Do  not  try  to  draw  150  ma.  when  the  meter  is  set  for 
a  maximum  of  15  ma.  If  the  pointer  gets  bent,  due  al- 
lowance must  be  made  in  reading. 

Electric  Circuit. — An  electric  circuit  consists  of  some 
sort  of  a  generator  and  a  more  or  less  complex  conducting 
path  between  its  terminals.  Electricity  outside  a  gener- 
ator always  passes  from  high  to  low  voltage,  and  the  cur- 
rent may  properly  be  said  to  lose  voltage  en  route  from 
one  generator  terminal  to  the  other. 

Consider  a  very  simple  circuit,  Fig.  2,  consisting  of  a 
generator,  G;  generator  resistance  one-tenth  ohm,  two  other 


26 


U.  S.  ARMY  X-RAY  MANUAL 


resistances  as  shown.  The  fundamental  law  of  such  a 
circuit  is  that  if  when  the  switch,  S,  is  open  we  have,  say 
220  volts,  then  for  any  total  resistance,  B,  we  will  have 
a  current,  on  closing  S,  such  that 

Current  x  total  resistance  =  220,  or  in  this  case, 
No.  of  amperes  x  (.1  +  .9  +  19)  =  220 
Current,  /  =  220  =  11  amperes. 
W 

The  voltage  is  used  up  as  follows: 

In   the     generator   11  x  .1  =      1.1  volts 
Between  A  and  B  11x19  =  209.0 
Between  B  and  C  11  x  .9  =     9.9 


Total 


220.0  volts 


Tig.  3.     Current-time  curve  of  a  simple  a.e.  circuit. 

This  relation  is  true  for  all  circuits,  viz.,  volts  lost 
due  to  resistance  of  B  ohms  when  a  current  of  I  amperes 
is  flowing  =  I  B. 

Direct  Current  (d.c). — When  the  electron-flow  is  in 
only  one  direction,  the  current  is  named  direct.  Dry  cells, 
storage  batteries,  static  machines,  and  d.-c.  dynamos  deliver 


X-RAY  PHYSICS  27 

direct  current.  A  current  may  be  intermittent  or  pulsat- 
ing, and  still  be  called  a  direct  current. 

Alternating  Current  (a.c). — When  the  electrons  flow 
in  one  direction  for  a  short  time  and  then  the  flow  de- 
creases and  a  reverse  flow  occurs,  we  say  the  current  is 
alternating.  A.-c,  dynamos  are  the  only  sources  of  true 
alternating  current. 

Such  a  current  in  its  simplest  form  may  be  pictured 
by  a  suitable  time-current  diagram.  In  Fig.  3  time  is 
shown  as  increasing  from  left  to  right. 

Let  OC  =  second 

60 


Then  OC  =BD  =CE  =P^  P^  =-^  second 

This  current  takes  all  its  variable  values  once  in  1/60 
of  a  second,  and  repeats  the  operation  60  times  in  one 
second.  It  is  designated  as  60  cycle  a.  c.  If  drawn  from 
a  220  volt  service,  its  complete  designation  is  220  volt — 
60  cycle — alternating  current  of  a  certain  number  of 
amperes. 

During  the  times  OB,  CD,  EF,  etc.,  current  flows  in  the 
opposite  sense  to  that  during  the  times  BC,  DE,  etc.  Note 
that  there  are  two  alternations  to  each  cycle,  or  120  per 
second  in  this  case. 

X-Ray  Current-Voltage  Requirements. — At  present  x- 
ray  tubes  are  used  with  currents  varying  approximately 
between  5  and  100  milliamperes,  and  at  voltage  running 
between  25  and  100  kv.,  i.  e.,  25,000  to  100,000  volts.  This 
high  voltage  requirement  cannot  be  met  by  simple  d.-c.  gen- 
erators. 

High  Voltage. — The  requisite  voltage  is  secured  by  the 
use  of: 


28  U.  S.  ARMY  X-RAY  MANUAL 

1.  The  so-called  static  machine  (direct  but  impractical). 

2.  The  periodic  interruption  of  a  direct  current  through 
one  coil,  causing  high  voltage  in  a  neighboring  coil  (in- 
duction coil). 

3.  Using  a  low  voltage  alternating  current  in  one  coil 
and  getting  a  high  voltage  alternating  in  an  adjacent  coil 
(transformer). 

The  second  device  is  still  used  to  some  extent,  but  has 
largely  been  displaced  by  the  transformer  in  recent  years. 
The  use  of  an  induction  coil  or  a  transformer  to  in- 
crease voltage  involves  two  distinct  circuits,  one  connected 
through  some  control  device  to  the  supply  line  or  genera- 
tor, and  known  as  the  primary  circuit ;  the  other,  insulated 
from  the  primary  and  connected  to  the  tube  terminals, 
known  as  the  secondary  circuit. 
The  primary  always : 

Is  of  relatively  low  voltage. 
Is  a  moderately  large  wire. 
Carries  a  current  of  some  amperes. 
Is  reasonably  safe  to  touch. 

Requires  good  metallic  contacts  at  all  connections. 
The  secondary  always: 
Is  high  voltage. 
Is  quite  a  small  wire. 
Carries  a  current  of  some  milliamperes. 
Is  unpleasant  and  often  dangerous  to  touch. 
"Will  pass  current  across  loose  connections  or  even 
through  some  insulating  material. 
The  induction  coil  and  a  few  transformers  have  both 
coils  wound  on  hollow  concentric  cylinders,  the  primary 
within  the  secondary,  and  the  space  inside  the  primary 
coil  is  filled  with  thin  iron  sheets  or  wires.     These  are 
named  open  magnetic  circuit  devices. 

Most  transformers  now  in  use  have  the  iron  in  the  form 


X-RAY  PHYSICS 


29 


of  a  closed  rectangle,  and  the  two  coils  wound  so  as  to 
slip  on  the  sides  of  this  rectangle.  These  are  known  as 
closed  magnetic  circuit  transformers. 

The  Gas  Tube. — While  a  great  variety  of  special  forms 
of  gas  containing  tubes  have  been  introduced  from  time 
to  time,  the  general  form  shown  in  Fig.  4  alone  has  sur- 
vived for  ordinarv  use. 


1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 
10. 
11. 
12. 
13. 


Fig.  4.     Eegular  gas  containing  tub€. 

Negative  or  cathode  terminal. 

Cathode  of  aluminum. 

Adjustable   connections  for  softening. 

Softening  material. 

Sealing  off  tip. 

Auxiliary  anode. 

Copper  block. 

Tungsten  button. 

Positive  or  anode  terminal. 

Anode  neck. 

Cathode  neck. 

Cathode  particles. 

Path  of  x-rays. 


A  L  M,  Anterior  hemisphere  showing  fluorescence. 


30 


U.  S.  ARMY  X-RAY  MANUAL 


The  target  material  has  a  great  influence  on  the  be- 
havior of  the  tube  and  the  quality  of  the  rays.  The  atomic 
weight  must  be  high,  as  the  fraction  of  cathode  ray  energy 
transformed  into  x-rays  increases  with  increase  of  atomic 
weight.  The  melting  point  must  be  high  or  the  metal  will 
melt  at  the  focus.  It  should  conduct  heat  well,  and  must 
not  vaporize  readily  below  its  melting  point.  The  follow- 
ing table  gives  the  approximate  data  relating  to  possible 
metals  for  this  purpose.  Taking  platinum  as  a  standard 
radiator: 


Amount  of 

Metal 

At.  Wt. 

X-Radiation 

Melting  Pt 

Platinum 

195.2 

1. 

1760.  C. 

Iridium 

193. 

.98 

2300 

Osmium 

190.9 

.97 

2700 

Tungsten 

184. 

.91 

above 

3000 

Tantalum 

181. 

.90 

2900 

The  essential  features  of  all  modern  tungsten  target  gas 
containing  tubes  are  shown  in  Fig.  4.  Various  minor 
modifications  may  be  seen  in  tubes  from  different  mak- 
ers, but  each  part  shown  must  be  present  in  some  form. 

The  cathodes  may  differ  in  shape,  but  only  aluminum 
gives  good  results  and  long  tube  life.  The  mounting  of 
cathode  and  target  must  be  firm,  and  the  position  in  the 
neck  carefully  chosen.  The  adjustable  arm  (3)  is  often 
absent,  and  a  third  wire  is  run  to  a  variable  spark  gap 
connecting  with  the  negative  terminal  of  the  machine. 
The  auxiliary  anode  (6)  has  a  great  variety  of  forms; 
in  many  water-cooled  tubes,  and  sometimes  in  others  (6) 
and  (10)  are  interchanged.  Numerous  special  devices  for 
conducting  heat  away  from  the  target  are  in  use  and  are 


X-RAY  PHYSICS  31 

more  or  less  effective.  For  treatment  or  for  long  fluoro- 
scopic examination  with  this  type  of  tube,  water  cooling 
is  essential,  and  a  good  stream  of  air  directed  against  the 
glass  adjacent  to  the  cathode  is  also  of  considerable  as- 
sistance. A  satisfactory  tube  must  have  a  stable  position 
of  anode  and  cathode ;  all  attempts  to  use  an  adjustable 
cathode  have  been  unsatisfactory.  The  metal  parts  must 
be  pre-heated  and  the  tube  itself  heated  during  exhaustion. 
A  well  made  and  properly  exhausted  tube  shows  a  good 
hemisphere  on  the  anterior  portion,  and  the  remainder  of 
the  tube  should  show  but  little  fluorescent  light ;  a  working 
tube  should  not  be  "flashy"  or  "cranky."  AYlien  one 
attempts  to  operate  a  moderately  hard  tube  at  too  low 
potential,  this  unstable  state  may  result  and  either  the 
voltage  must  be  raised  or  the  tube  softened.  The  vacuum 
must  be  within  fairly  well-defined  limits,  averaging  not 
far  from  .001  mm.  pressure  of  mercury,  and  must  be 
in  some  manner  under  control,  if  the  life  of  the  tube  is 
of  consequence. 

The  tendency  of  all  gas  containing  tubes  on  low  current 
is  to  "harden,"  i.  e.,  to  require  more  voltage  for  the  same 
current,  or,  if  the  voltage  is  not  changed,  the  current  de- 
creases. On  operation  above  a  certain  power  peculiar  to 
each  tube,  the  tube  softens  on  account  of  heating;  when 
this  proceeds  so  far  that  the  tube  shows  and  maintains 
a  purple  gloAV  marking  out  the  cathode  stream,  it  is 
useless  until  repumped. 

Many  devices  have  been  used  to  soften  tubes.  The  more 
common  are  the  following: 

1.  A  side  tube  containing  mica,  asbestos,  etc.,  and 
through  which  a  small  discharge  current  may  be  sent, 
thereby  liberating  gas.     (No.  4,  Fig.  4.) 

2.  A  special  target  is  placed  in  a  side  tube  to  be  bom- 
barded by  rays  from  a  small  auxiliary  cathode. 


32  U.  S.  AR]\IY  X-RAY  MANUAL 

3.  A  fine  palladium  tube  projects  through  the  walls 
of  the  tube;  when  this  is  heated  by  a  small  flame  it 
allows  hydrogen  to  pass  into  the  bulb.  This  has  been  modi- 
fied by  Snook,  where  the  tube  is  heated  by  a  spark  dis- 
charged from  the  operating  transformer. 

4.  Heating  the  entire  bulb.  (Useless  except  in  an 
emergency.) 

5.  A  mercury-controlled  porous  valve  allows  air  to  pass 
slowly  into  the  bulb  when  the  inlet  is  not  covered  by  the 
mercury   (Heinz-Bauer). 

2,  3,  and  4  are  rarely  used  in  this  country,  although  3 
(osmosis  regulators)  are  sometimes  seen  outside  the  more 
useful  Snook  form. 

The  Coolidge  Tube. — The  great  difficulty  in  the  opera- 
tion of  the  ordinary  gas  containing  tube  lies  in  the  ir- 
regular supply  of  electrons  and  the  impossibility  of  control 
of  their  development.  When  operated  above  very  mod- 
erate power,  the  trend  is  always  toward  larger  quantities 
of  electrons  and  a  consequent  drop  in  penetration,  unless 
the  current  is  greatly  increased,  when  a  still  greater  sup- 
ply is  developed,  so  that  there  is  no  automatic  self-pro- 
tection of  the  tube. 

Wehnelt  found  that  a  platinum  ribbon  coated  with  lime 
would  allow  of  current  transfer  through  a  high  vacuum 
at  nioderate  voltages.  Several  attempts  to  use  such  a 
cathode  for  x-ray  tubes  were  unsuccessful,  and  no  modifi- 
cation of  the  standard  tube  appeared  until  it  was  found 
by  Richardson  and  others  that  electrons  were  emitted 
by  hot  metals. 

The  simplest  application  of  this  principle  to  x-ray  de- 
velopment has  been  worked  out  by  Dr.  W.  D.  Coolidge  in 
the  Research  Laboratory  of  the  General  Electric  Company 
at  Schenectady.  In  this  tube,  the  cathode  is  a  spiral 
filament  of  tungsten  wire,  A,  Fig.  5,  heated  to  a  high  tern- 


X-RAY  PHYSICS 


33 


perature  by  a  current  from  an  insulated  storage  battery, 
or  by  a  special  transformer.  The  form  of  electrostatic 
field  needed  for  focussing'  the  electron  stream  is  fixed  by  a 
small  molybdenum  cylinder,  B,  within  which  the  cathode 
is  placed.  The  target  is  usually  a  solid  piece  of  wrought 
tungsten  mounted  on  a  molybdenum  rod,  around  which 
collars  are  placed  to  distrib- 
ute the  heat  conducted  from 
the  target. 

Fig.  6  shows  the  Coolidge 
tube. 

Cathode  terminal. 


1. 
2. 
3. 
4. 
5. 


Fig.  5. 
Electron  focusing"  cone,  struction. 


Coolidge     cathode     con- 


Solid  tungsten  target. 

Mol^^bdenum  supporting  rod. 

Anode  terminal. 
In  order  to   operate  properly,   it  was  found  that  the 
highest  possible  vacuum  must  be  attained.    Not  only  was 
the   greatest   care   required   in   pumping,   but  the   metal 


Fig.  6.     Coolidge  tube. 

parts  had  to  be  freed  from  occluded  gas  by  heating  in  a 
vacuum  nearly  to  their  melting  point.  In  this  tube  there 
is  no  source  of  electrons  except  from  the  hot  filament, 
and  as  this  supply  depends  only  on  the  temperature  of 
the  filament,  the  operator  has  perfect  control  of  the  num- 
ber of  available  electrons  by  simply  changing  the  auxiliary 


34 


U.  S.  AmiY  X-RAY  MANUAL 


current.  A  small  transformer  is  now  generally  used  to 
supply  low  voltage  for  the  filament  current.  Connections 
are  as  shown  in  Fig.  7.  The  winding  connected  to  the 
filament  must  be  well  insulated  from  case  and  primary 
winding. 

The  current  through  the  tube  cannot  be  increased  after 


FILF)MBNT 


ZZO  VOLTS 


Fig.  7.     Wiring  diagram  for  step-down  transformer  to  supply  cur- 
rent for  filament  of  Coolidge  tube. 


the  supply  of  electrons  is  entirely  utilized,  no  matter  how 
much  the  voltage  is  raised.  This  maximum  current  for 
each  particular  filament  temperature  is  named  the  satura<- 
tion  current,  and  until  this  is  reached  the  voltage  main- 
tained between  cathode  and  target  may  be  too  low  for 
use.  So  long  as  the  negative  current  reaching  the  tube 
does  not  exceed  the  number  of  electrons  emitted  per  sec- 


X-RAY  PHYSICS  35 

ond  multiplied  by  the  charge  of  each  electron,  there  can  be 
no  charge  piled  up  on  the  electrodes — i.  e.,  no  effective 
terminal  voltage. 

No  Inverse. — A  further  valuable  feature  of  the  tube 
is  its  inability  to  transmit  inverse  so  long  as  the  focal  spot 
is  not  too  hot.  On  account  of  the  increased  strain  on 
the  glass,  when  inverse  is  present,  it  is  well  to  include 
a  valve  tube  when  operating  on  a  heavy  coil. 

Penetration  Limits. — The  highest  operating  voltage  on 
the  present  tubes  is  about  100  kv.,  as  measured  on  a  spe- 
cial electrostatic  voltmeter.  This  refers  to  ' '  effective ' '  volt- 
age; the  peak  voltage  is  larger  than  this. 

No  doubt  this  can  be  increased  by  modification  of  the 
design,  but  insulation  difficulties  and  danger  of  puncture 
will  be  increased  as  higher  voltages  are  used.  Such  high 
penetrating  rays  as  may  now  be  reached  are  not  useful  in 
fluoroscopic  work  or  in  radiography,  partly  on  account  of 
the  enormous  amount  of  scattered  radiation  developed  in 
the  tissues  of  the  body.  Such  scattered  and  corpuscular 
rays  may,  however,  be  useful  in  therapeutic  work.  Very 
soft  rays  may  be  produced  in  great  abundance  if  the  glass 
will  allow  them  to  pass  out.  Attempts  to  use  too  soft  rays 
in  radiographic  work  are  always  fraught  with  grave  dan- 
ger. 

No  Fluorescence  in  the  Glass. — In  marked  contrast  to 
the  usual  tube,  there  is  no  fluorescence  of  the  glass  walls 
except  a  slight  illumination  in  the  anode  neck.  Some- 
times a  minute  chip  in  the  glass  or  a  slight  evolution  of 
tungsten  vapor  will  give  a  momentary  flash  of  green,  but 
on  further  operation  at  moderate  power  this  disappears. 
The  bombardment  of  the  walls  of  the  tube  by  electrons 
reflected  from  the  target  or  scattered  from  the  gas  atoms 
in  the  gas  containing  tube  is  the  cause  of  the  fluorescence 
and    of    a    very    considerable    amount    of    soft   radiation 


36 


U.  S.  ARMY  X-RAY  MANUAL 


originating  in  the  glass.  As  there  is  in  a  gas  tube  as  large 
a  supply  of  positive  ions  as  of  negative,  continual  recom- 
bination results,  and  no  negative  layer  can  form  on  the 
glass  walls  to  prevent  bombardment  by  scattered  and  re- 
flected electrons.  In  the  Coolidge  tube  the  absence  of  posi- 
tive ions  probably  allows  the  accumulation  of  a  negative 
charge  on  the  glass,  and  as  soon  as  established  this  layer 
repels  electrons  and  the  glass  is  no  longer  a  target. 

Nev^  Form  of  Coolidge  Tube. — The  ordinary  form,  of 
Coolidge  tubejwill  opera,te_satisfactorily  without  a  rectifier 
if  the  focal  spot  is  at  a  tenvgeratiire  helow^thait  ai  which  it 
gives  off  an  appreciaMe  nun^er  of  electrmis.  It  follows 
that  part  of  the  problem  of  eliminating  the  rectifier  is  keep- 


TiG.  8.    Eadiator  type  of  Coolidge  tube. 

ing  the  target  cool.  A  new  form  of  tube  which  will  help 
greatly  in  this  mode  of  operation  has  recently  been  de- 
veloped by  the  General  Electric  Research  Laboratory,  Fig. 
8.  The  target  is  a  tungsten  button  set  in  a  heavy  copper 
backing  which  is  continuous  with  a  large  copper  rod  ex- 
tending out  of  the  tube  neck.  To  this  are  attached  a 
series  of  discs  acting  as  radiators.  Operated  within  limits 
set  by  the  manufacturers,  this  tube  su^jDresses  coi^pletely 
each  alternate  half  wave  and  may  be^  operated  direct  on  a 
suitable  transformer.  At  present  these  are  designed  for 
10  ma.  at  a  5-inch  gap  for  radiographic  work,  and  for 
5  ma.  at  the  same  gap  for  continuous  duty  in  fluoroscopy. 
The  wiring  diagram  then  becomes  very  simple  and  easily 
understood. 


X-RAY  PHYSICS 


37 


In  Fig.  9  are  shown  a  current-time  curve  and  a  voltage- 
time  curve  for  the  self-rectifying  tube.     In  the  latter  OA^fJi^^J^  ^ 
is  the,  working  jpeak  voltage   which   determines  the  tube 
radiation,  and  BC^is  the  peak  voltage  of  the_suppressed 
wave  ^whichwpuld  giye  the  spark  gap  reading. 

A  transformer  should  be  used  which  will  not  vary  its 


o,A .     '^.e.^  >L.*«.^^i^  i.c/7U:e<  -,:;;^  0,^A^t^ 

A 


Fig.  9.  Current  and  voltage  curve  for  self -rectifying  Coolidge 
tube.  The  voltage  difference  indicated  by  the  excess  of  BC  over  OA 
will  depend  on  design  of  transformer  and  control. 

voyage  too  much  from^jjjjjjurrent  to  that  needed  to  oper- 
ate_^it  properly,  sinc^e  t_he^,^ltage  of  the  suppressed  wave 
is  quite  decidedly  higher  thanjhat  ofthe  one^used,  there- 
by causing  spark-over  and  giving  an  incorrect  idea  of  the 
actual  working  voltage. 

The  value  of  this  arrangement  for  field  work  can  hardly 
be  overestimated,  as  there  is  no  heavy  and  complicated 
rectifier.     Operated  from  a  small  gas  engine-driven  gen- 


38  U.  S.  ARMY  X-RAY  MANUAL 

erator,  it  is  ideal  for  fluoroscopic  work  and  satisfactory  for 

emergency  radiography.     See  U.  S.  Army  Portable  Unit, 

page  167. 

yj^^tUh   Tube  Focus. — The  x-ra^ys  cannot  be  focussed  by  any 

known  method,  so  that  the,  terin£  fpcal_j)mntj__etc.,  are  mis- 

-^iL*jl|leading.     Electrons  can,j3e^  directed  by  s^uitable  cathode 

,^       construction  so  that  the  greater  portion  strike  a  small  area 

tiA,     oiTL  the^Jarget.     The   diameter  of  this  area  is  known  as 

.|5^the  ''focus,"  and  it  is  customary  to  speak  of  broad,  me- 

V^     dium,  and  fine  foci.     One  can  hardly  state  precise  limits 

^         between   these   designations,   but   anything  below   3   mm. 

'  would  be  extra  fine  focus ;  3  to  4  mm.  fine  focus ;  4  to  7  mm. 

medium  focus;  and  over  7  mm.  broad  focus. 
^,^1^^'^^he  size  of  focus  is^foundjDy  the  use  of ,  a  pin-hole  cam- 
\.j<       era,  "and  ^ould  be  giyep.  by  the  maker.     Its  size  is  im- 
pKJ^^  j)ortafl,t.  in  two  ways :     First  in  relation  to  the  sharpness 
'/^^^^^^of^jmage  on  plate  or  screen ;  second,  as  fixing  thejower 
I  'that  may  be  used  wftKout 'damage  to  the  target.    When  an 
electron  stream  is  maintained  at  high  velocity  against  the 
^,,t,^)T^^  target,  there  is  a  rapid  rise  in  temperature  which  may 
^uutkt  result  m  vaporization  or  fusion  of  the  metah     The  rate 
of  removal  of  heat  by  conduction  is  increased  by  broaden- 
ing  the   focal   spot^   and  the_  amount   of  jnetal   suffering 
extreme  rise  in  temperature  ^s  increased,  so  that  for  two 
^     reasons  there  is  less  danger  of  target  damage. 
r^^^^^  ^     The  effect  on  sharpness  of  image  is  shown  by  using  an 
exaggerated  diagram  as  in  Fig.  10.    F^  Fg  are  the  bound- 
aries of  the  focal  spot  and  1-2  is  the  object.     With  the 
plate  in  plane  A,  had  the  only  source  been  a  point,  i^^,  a 
sharp   shadow  PQ   would  result;  had  F^  been  the  only 
source,  then  BS  would  result.     The  only  portion  entirely 
shaded  is  BQ,  and  if  the  object  is  round,  we  have  a  cen- 
tral white  spot  with  a  variable  shading  out  to  a  diameter 
PS.    If  the  focal  spot  were  very  wide  and  the  object  very 


iA|Me^< 


X-RAY  PHYSICS 


39 


small  a  plane  B  could  be  found  beyond  which  there  would 
be  no  white  image. 

The  ring  PE  and  QS  is  narrower  the  closer  the  object 
to  the  plate,  the  smaller  the  focal  spot  and  the  greater 
the  target-plate  distance.  The  apparent  size  of  the  shadow 
will  vary  somewhat  with  exposure,  as  regions  partly  shaded 
may  be  under-exposed  when  the  exposure  is  brief  and  the 
true  shadow  may  not  appear  at  all. 


Fig.  10.     Variation  of  size  of  shadows  of  small  objects  when  a  wide 
focus  is  used  close  to  the  plate. 


Fine  focus  tubes  are  not  needed  in  gastro-intestinal 
work,  and  should  be  used  in  other  work  with  such  care 
that   the   target   does   not  become   pitted. 

Conditions  for  Operation. — Two^thingsjnust_be  consid- 
ered in  the  operation  of  x-ray  tubes.  The  first  is  a  proper 
supply  of  electrons  as  current  carriers,  the  second  a  proper 
electric  drive  to  force  theseelectrons  against  the  target. 
These  tw^o  must_be_so_related  to  each  other  that  a  proper 
voltage_  can  be  maintained  when  current  is  actually  used. 

No  amount  of  milliamperage  will  serve  todol^aMograpMc 
or  fluoroscopic  work  without  a  proper  voltage  consumptiooi 


40  U.  S.  ARMY  X-EAY  MANUAL 

at   the   tube.     The    potential    difference    or   voltage   drop 
across  the  tube  is  due  to  a  piling  up  of  positive  charges 
and  electrons  at  the  target  and  cathode  respectively  and 
this  must  be  done  by  the  generator.    When  elect^rons  move 
across  from_jcathode  to,  target^they  tejid^t^  relieve  the  con- 
ioii4r.>tyf  ^estion  and,  if  the  generator^^hould  fail  to  maintain  the 
^**^i***L^PP^^'  the  voltage  and^charge  would  disappear.   The  great- 
*  *^*J^.ZL^^  the  number  of  elej3trons  passing  across  in  a  given^time, 
^he  more  the  terminal  voltage  will  be  reduced  for  a  given 
ability^  of  jtlie^  generator  to  pump   a  new  supply.     The 
current  is  the  charge  of  one  electron  multiplied  by  the  num- 
ber passing  per  second.    Hence  the  greater  the  milliamper- 
age,  the  greater  the  power  demanded  from  the  generator 
to   maintain   voltage   and  the   more   the  drop  in  voltage 
from  that  shown  on  open  circuit  or  on  small  current. 

When  the  current  increases,  irrespective  of  the  type  of 

tube  used  or  the  design  of  the  machine,  the  operating 

voltage  will  be  reduced  unless  the  rheostat  or  autotrans- 

former  control  is  moved  to  apply  more  power  to  the  pri- 

>W'        mary.     The  spark  gap  on  open  circuit  is  no  guide  to  the 

^^"^^hility  of  the  transformer  or  induction  coil  to  keep  lip 

ju^^^i^'^oltage  whenj:urreni  is  drawn. 

Inasmuch  as  reduced  voltage  very  much  more  than  off- 
sets the^ffect  of  change  ^f  current_in  x-ray  production 
as  regards  quantity,  and  likewise  decreases  the_ability  to_ 
pass  through  maTerial,  tlie  proper  maintenance  of  volt- 
age is  the  mqs^indisj)ensable_ requisite  in^ny  x-ray  instal- 
lation. By  increasing  exposure  time  nearly  all  work  may 
hejproperly  done  at  low  current,  hut  no_increase_  of  expo- 
sure time  will  compensate  for  too  low  voltage. 

The  transformer  must  be  designed  for  the  voltage  supply 
on  which  it  is  used,  and  it  is  very  essential  that  the  proper 
terminal  voltage  on  the  transformer  primary  should  be 
maintained  at  all  times  and  at  all  loads.    After  a  machine 


X-RAY  PHYSICS  41 

is  once  installed  the  operator  has  no  control  over  these 
matters.  The  size  of  wire  required  to  transmit  current 
from  the  usual  power  transformer  to  the  x-ray  room  will 
depend  on  the  distance  between  the  two  transformers  and 
on  the  voltage  used.  To  transmit  the  same  power  at  110 
volts  as  at  220  will  require  twice  the  current.  Whenever 
a  given  current  is  passed  over  a  resistance  there  is  a  volt- 
age drop  or  loss.  This  loss  is  greater,  the  greater  the  cur- 
rent and  the  greater  the  resistance.  When  the  line  resist- 
ance and  the  current  are  known  the  voltage  loss  is  found 
by  taking  their  product.  A  loss  of  2  or  3  per  cent  of  the 
line  voltage  may  be  permissible.    See  line  wiring,  p.  70. 

The  operator  must  take  care  that  the  current  through 
the  tube  does  not  drop  the  potential  too  much  for  the 
work  required.  For  increased  tube  current  the  rheostat 
or  autotransformer  setting  must  be  raised  accordingly. 

Gas  Tube  Characteristics. — The  earlier^  type^ofjtube de- 
pended for  iXs_supply  of  electrons  on  the  breakdown  pf  the 
atoms  of  its  gaseojas_atmosphere,  whereby  the_electrons  and 
the  positive  remainder  of  the  atom  were_separated  and 
driven  in^oppo^ite  directions.  This  breakdown  or  ioniza- 
tion_may  be  ^_ae_to^evera_l_caiises : 

1.  The  high  electric  stress  between^  cathode  and  target. 

2.  Th^  shooting  qf^ectrons  through  tSe~atmosphere. 

3.  The  passage  of  x-rays  th^ugh^heatmosphere. 

The  number  of_electrons  set  freejwill  depend  onjhe  tubeXJJ   ^ 
vai^uum.     If  too  few  can  be  had,  the  tube  is  of  too  high  ^-y^-- -■^*- 
vacuum  and  is  called  ''hard."     It  backs  up  a  very  high      '**«*< 
spark  gap,  and  may  become  ''cranky."     If  too  much  gas   /      -r-^ 
Js__^resent   the^j3ibe__cari^ies  so   much   current  '^^^^\_}^-^i\l^rA 
quit e_  imp osjible_  to   keep    up    voltage.      The   amount   of  j 

free  gas  in  th^  tube  will  increase  as  the_^parts_QfJliejtub-e  ^ 

nse_  in^  temperature,   since  gas  'to^^to^tickjto^a^^^ld 


42  U.  S.  ARMY  X-RAY  MANUAL 

surface.      Therein   often   lies^  the_explanation   of   failure 
injradiography  on^prolon^ed^  exposure. 

The  rate  of  soJ1;£iiJ,ng  of  a  gas  tiibe  operated  at_a_glven 
initial  current  an^  vglta^e^  varies  with_jts  original  ex- 
haustion and  its  use  afterward.  On  low  power  with  small 
eurrent~and  high  voltage^there  is  a  marked  tendency  to 
reduce  the  amount  of  free_gas  and  thus  raise^the  vacuum. 
"When  this  tendency  is  just  balanced  by  the  evolution  or 
release  of  gas  by  Jieat  the  tube  runs  at  a  nearly  uniform 
current_and_voltage.  On  slightly  higher  power  it  will 
soften  and  the  rate  of  softening  will  generally  be  greater 
with  a  new  tube  than  in  case  of  a  well-seasoned  one. 
^  4^~{  Danger  in  Testing". — It  is  unwise  to  t^t  a  gas^tube  at 
[^T^^^^^^^  the  power  used  in  gastrO;^intestinal  or  other  h^avy  work, 
1^  as  ijt  is  Hkely  to  ov^^often  before  a  min.ij,mmeter  can  1)^ 
r^ad  or  s£aj;k  gap  really  ascertained.  The  usual  recourse 
is  Jo^note  current  and^^ap  at  low  power,  and  assume 
that^whjn^this  is^roperly  adjusted  on,  say,  button_^X, 
it  will  give  a  proper  result  on  a  higher^utton  Y.  Careful 
study  of  these  tubes  ^ows  that  this  is  only  approximately 
the_case,  for  not  only^will  tubes  vary  one  from  another, 
baJLjhe  same  jube  will  behave  differently  on  different 
days.  No  better  method  has  "IBeen  suggested,  however, 
so  the  operator  should  endeavor  to  season  a  tube,  if  pos- 
sible, before  attempting  fast  work. 
1:,  Coolidge  Tube  Characteristics. — The_electron  supply  in 

Uyijr.^  the__Coolidge  type_of  Jiot  ^cathode  tube  i^_due7enferely  to 
the  hot  tungsten  filainent,  as  all  the  gas  it  is  possible  to 
remove  has  been  taken  out  in  pumping.  The  current  car- 
ried by  the  tube  isjimited  by  the  rate  of  electron  supply 
and  is  thus  determined  sole2x  hy  the  filament  current. 
This  maximum  tulje  curjent  at  a  given_  filament  current  is 
^ly  attained  a^a  sufficiently  high  voltage  and  this  voltage 
increases  as  the  filament  temperature  is  raised.    When  all 


rtn 


X-RAY  PHYSICS 


43 


the  electrons  are  being  driven  across  as  fast  as  they  are 
produced,  the  correspondhig  curren^t  is  named  the  satura- 
tion current.  After  s^uch  a  cuiTent_ is_ reached Jh^voltage 
may  be_^reatl^increased_ without  a  rise  in  tub^current. 
Fig.  11  shows  this  characteristic  of  the  tube",  quite  different 
from  the  gas-containing  tube  where  higher  applied  voltage 


Fig.  11.     Current-voltage  lines  of  Coolidge  tube  for  fixed  filament 
temperatures.     Vertical  portions  are  above  ''saturation"  points. 

brings  increased  current.  On  account  of  the  great  increase 
of  tube  current  resulting  from  a  slight  rise  in  filament 
current  the  writer  has  found  it  impractical  to  depend  on 
the  filament  ammeter  as  a  guide  to  tube  current,  especially 
when  using  rheostat  control.  In  fact  better  work  is  done 
where  no  dependence  is  put  on  anything  except  spark  gap 
and  tiihe  current.  -^        .     ^ 

Outflow  of  Radiation. — As  radiation  proceeds  from  the  Cyt^^ 
•igin  on  the  target  it  spreads  out  and  flows  through  the  ^  iix.'^' 

/ 


origin 


'^O^-c^ 


44  U.  S.  ARMY  X-RAY  IMANUAL 

*^  surfaces  of  larger  and  larger  spheres.  The  amount  re- 
ceived in  a  given  time  hy ^wy^iixcd  area jthen  decreases 
as  thQ_distancg^  of  the_receiving  .surface  is  greater.  This^ 
decrease  always  follows  the  inverse  square  law.  Thus  if 
100  arbitrary  units  reach  a  given  area  at  10  inches  from 
the  target,  the  same  area  20  inches  from  the  target  will 
only  get  i/4  ^s  much  in  the  same  time,  i.  e.,  25  units.  At 
30  inches  the  same  area  receives  but  1/9  as  much  or 
11  1/9  units.  Or  to  get  the  same  radiation  to  this  area  at 
the  increased  distances  the  time  must  increase  as  the  square 
of  the  distance,  i.   e.,   if  at  15  inches  2  seconds  are  re- 

—       =  2  X  —   ,  at  25  inches 

2  X   —  ,  at  30  inches  2x     /-—    jr=2x4  =  8  seconds, 

etc. 

Amount  of  Radiation. — The  measurement  of  x-ray  radi- 
ation has  proved  a  rather  difficult  matter  and  need  not 
be  fully  discussed  here.  For  our  purpose  the  photographic 
measure  is  sufficiently  accurate  and  determines  the  useful- 
ness of  the  rays  in  practice.  Whatever  the  conditions  of 
operation,  we  might  take  a  time  of  exposure  so  as  to  get 
the  same  blackening  on  two  spots  on  a  photographic  plate, 
and  then  say  that  the  two  had  the  same  exposure,  when 
exposure  does  not  mean  time  of  tube  action  alone. 

Such  a  method  measures  only  the  effect  of  rays  used  in 
changing  the  emulsion,  not  the  total  beam,  the  greater 
portion  of  which  passes  through  the  film. 

Quality. — Fully  as  important  as  the  amount  of  radiation 
is  the  quality  or  distribution  of  radiation  among  various 
wave  lengths.  Quality  determines  the  ability  of  the  rays 
to  pass  through  flesh  and  bone,  and  was  roughly  gauged 
by  the  use  of  penetrometers.  It  depends  on  the  voltage 
used  to  drive  the  current  across  the  space  between  cathode 


X-RAY  PHYSICS  45 

and  anode,  and  is  best  expressed  in  terms  of  voltage  or 
gap. 

Dependence  of  Quantity  on  Electrical  Conditions. — It 

is  very  important  to  realize  that  the  amount  of  radiation 
as  measured  by  the  photographic  effect  is  simply  related  to 
the  electrical  conditions  under  which  a  tube  is  operated. 
If  we  let   /  =  Current  in  milliamperes 
y  =  Effective  voltage  in  kv. 
Then  radiation  leaves  the  target  at  a  rate  depending  on 
the  product  of  current  and  the  square  of  the  voltage.    The 
amount  reaching  a  given  area  placed  at  right  angles  to 
the  flow  and  at  a  distance  d  from  the  target  and  in  a  time 

t  is  measured  by  — 7^— 
d^ 

Thus  if  7i,  =  40  ma.,  V^  =  30  kv.,  cZ  =  20  inches,  t  = 
1  second,  in  one  case,  and 

I^  z=z  10  ma.,  ¥2  =  60  kv.,  d  =  20  inches,  t  ^1  second 
in  another,  then  Q^,  =  40x30x30x  1/400  =  90  arbitrary 
units  where  Q^  =  amount  of  radiation  in  the  first  case 
and  §2  =  10x60x60x1/400  =  90  units  in  the  second 
case.  That  is,  40  ma.  at  30  kv.  and  10  ma.  at  60  kv. 
will  produce  the  same  quantity  of  x-rays  as  measured 
by  photographic  effect. 

However,  the  radiation  produced  at  60  kv.  is  better  able 
to  penetrate  any  piece  of  matter,  and  a  higher  percentage 
passes  through,  so  that  a  plate  exposed  partly  to  one  and 
partly  to  the  other  through  a  block  of  material  will  show 
much  more  darkening  for  the  second  case,  even  though, 
the  quantities  of  radiation  generated  at  the  tube  are  equal. 
It  would  darken  the  plate  equally  if  no  body  were  inter- 
posed. 

No  matter  what  amount  of  current  is  passed  through 
a  tube  it  is  useless  for  radiographic  or  fluoroscopic  work, 
unless  a  voltage  able  to  break  down  from.  2  to  6  inches 


46 


U.  S.  ARMY  X-RAY  MANUAL 

For  thick  parts  the 


of  mr  between  hlunt  points  is  used 
higher  voltage  (gap)  must  be  used. 

The  relation  of  sparking  distance  (between  blunt  points) 
to  kilovolts  is  shown  in  Fig.  12.  The  kilovoltage  is  approxi- 
mately ten  times  the  gap  in  inches  plus  ten. 

Penetration. — The  most  characteristic  feature  of  x-rays 

e 


IN. 
6 


-   - 

TTj 

:"■"■■■:"•"": 

■"-;'=: 

iTrr 

T 

I: 

::;:: 

;= 

----:--:  :::::"3::: " 

4-:; 

i.<f;:;:; 

Wli 

:: 

w 

::::: 

I  ■ 

> 

;;;; 

;; 

^ 

r 

„  .irt-+t-- 

[■: 

W 

: 

■B 

:::: 

:: 

-.'. 

:::::::i:::|l  + 

II 

: ::: 

;: 

TT 

::::::::::::::::::: 

\W 

:: 

1± 

MMM. 

i  :i 

w 

1 

'---^TT 

".'.'.'. 

:: 

;::;;-:i--:::;;;ii;:;^? 

\\ 

i 

\l 

Hi: 

:: 

\l 

----- 

\l 

:::::::::::::::::: 

Hi! 

:: 

■,--.-- ±Li::^:::::::  +  :::::i. 

:: 

:: 

::::::::; 

■T- 

':: 

iO      20     60     40     50     60     70     60     90     100 


K.V. 


Pig.  12.     Approximate    relation    between    effective    kilovolts    and 
spark  gap  for  moderately  blunt  points. 

is  their  ability  to  pass  through  material  quite  opaque  to 
other  types  of  radiation.  In  all  cases  there  is  some  absorp- 
tion, but  the  rate  of  absorption  or  the  amount  left  after 
passing  through  any  layer  of  material  varies  according  to 
the  composition  of  the  x-ray  beam.  The  most  penetrat- 
ing rays  are  produced  only  at  higher  voltages.  This  pene- 
tration could  be  accurately  defined  in  the  case  of  a  beam  of 
one  wave  length,  but  it  is  quite  difficult  in  the  case  of  an 
actual  complex  beam. 


X-RAY  PHYSICS  47 

It  is  essential  for  the  operator  to  realize  that  increas- 
ing the  tube  voltage  will  (a)  add  shorter  and  more  pene- 
trating rays;  (b)  increase  the  quantity  of  the  less  pene- 
trating which  were  produced  at  the  lower  voltage. 

X-Ray  Transformer. — There  is  no  practical  means  of 
directly  generating  an  electric  current  at  the  voltage 
needed  in  the  production  of  useful  x-rays,  hence  it  is  nec- 
essary to  use  a  transformer,  stepping  up  low  voltage  cur- 
rent to  the  high  voltage  required.  The  transformer  consists 
of  two  coils  of  wire  around  a  common  iron  core.  For  com- 
plete insulation  of  the  coils  from  each  other  the  system  is 
immersed  in  oil  or  in  wax.  If  in  the  latter,  it  is  shipped 
complete;  when  oil  insulated,  the  oil  is  usually  shipped 
separately.  In  this  case,  it  should  be  siphoned  into  the 
transformer;  the  inlet  side  should  be  raised  an  inch  or 
so  to  get  complete  expulsion  of  the  air.  It  is  well  to 
operate  at  a  low  power,  allowing  sparks  to  pass  across  an 
inch  gap  for  some  time  to  dislodge  small  air  bubbles  be- 
fore putting  it  into  service. 

Use  no  oil  not  furnished  for  the  purpose  by  a  reliable 
manufacturer;  the  oil  must  contain  no  moisture. 

Examine  the  oil  level  every  two  months  to  be  sure  it 
fills  the  tank.  An  exposed  coil  is  sure  to  break  down 
by  puncture  of  the  insulation.  The  top  of  the  case  should 
be  kept  free  from  oil  and  dirt.  For  protection  against 
surges  or  sudden  high  tension  pulses  which  are  likely  to 
damage  the  transformer,  a  resistance  should  be  placed 
in  shunt  with  the  low  tension  terminals.  If  this  is  not 
provided  by  the  maker,  ordinary  lamps  may  be  used.  Fig. 
13. 

The  middle  of  the  secondary  is  usually  connected  to  the 
case  (grounded)  ;  this  insures  a  distribution  of  potential 
equally  above  and  below  the  ''earth"  potential.  Thus,  if 
the  terminal  voltage  is  40,000  volts,  then  the  tendency  to 


48 


U.  S.  ARMY  X-RAY  MANUAL 


pass  a  spark  to  any  grounded  conductor  is  20,000  volts. 
This  arrangement  avoids  in  some  measure  the  tendency  to 
discharge  to  patient,  stand,  and  tube  that  would  result  if 
the  full  terminal  voltage  were  effective  to  earth. 

Care  must  be  taken  to  keep  all  contacts  on  the  low  volt- 
age side  tight.  See  that  low  tension  wires  are  kept  as  far 
away  from  the  high  tension  terminals  as  possible.  If 
trouble  actually  occurs,  due  to  short  circuit  or  break  inside 


Fig.  13.     Protection  from  surge  by  use  of  a  lamp. 


the  transformer,  there  is  no  use  in  trying  to  repair  it,  as 
a  rule,  unless  the  trouble  is  close  to  the  terminals.  If 
there  is  trouble  arising  from  sparking  across  between  the 
high  tension  terminals  of  the  transformer,  attaching  small 
spheres  will  relieve  the  tension  and  usually  cure  the 
trouble,  or  insulating  barrier  plates  may  be  used. 

Control  of  the  Transformer. — Corresponding  to  each  of 
the  various  high  tension  voltages  maintained  at  the  tube 
terminals,  there  must  be  applied  a  definite  voltage  across 
the  primary  of  the  transformer.  The  transformer  changes 
voltage  approximately  in  the  ratio  of  number  of  turns  in 
the  primary  to  number  of  turns   in  the  secondary,   and 


X-RAY  PHYSICS  49 

changes  current  in  the  inverse  ratio.  Thus  a  particular 
x-ray  transformer  might  be  wound  with  500  turns  in  the 
secondary  for  each  turn  of  primary,  and  it  would  be 
said  to  have  a  step-up  ratio  of  500.  The  secondary  volt- 
age would  be  500  times  the  voltage  in  the  primary  and  the 
secondary  current  1/500  of  that  in  the  primary. 

A  table  of  the  voltages  that  must  be  supplied  and  main- 
tained at  the  primary  terminals  to  give  various  high  tension 
voltages  can  easily  be  made  in  this  case. 

Primary  Resultant  Spark  Gap 

Applied  Voltage  H.  T.  Voltage  (approximate) 

80  V.  40  kv.  3       in. 

90  45  31/2 

100  50  4 

110  55  41/2 

120  60  5 

130  65  51/2 

140  70  6 

150  75  6I/2 

160  80  7 

220  110  10 

liDQO 

Such  primary  voltages  can  be  secured  from  a  line  sup- 
ply of  220  volts  (a)  by  the  use  of  a  rheostat,  (b)  by  the 
use  of  an  autotransformer. 

Rheostat. — The  rheostat  is  an  adjustable  resistance  used 
to  consume  a  part  of  the  line  voltage  and  leave  the  proper 
voltage  to  be  applied  at  the  transformer.  Suppose,  for 
instance,  it  is  desired  to  have  40  ma.,  at  a  5-inch  gap 
delivered  to  the  tube.  The  primary  must  be  supplied  with 
120  volts  and  a  current  of  40  ma.  x  500  =  20  amperes. 
In  this  case  the  rheostat  must  consume  100  volts  from  the 
220   volt  line  with  a  20   ampere   current,   Fig.   14.     By 


50 


U.  S.  ARMY  X-RAY  MANUAL 


Ohms  law  (V  =  IB)  the  voltage  consumed  in  the  flow  of 
current  through  a  resistance  is  equal  to  the  product  of  the 
current  in  amperes  and  the  resistance  in  ohms.  There- 
fore, 100  V  ^  20  X  R  from  which  R  ^  5  ohms,  hence  we 
would  need  5  ohms  of  the  rheostat  to  get  the  setting 
desired. 

The  rheostat  consists  of  coils  of  resistance  wire  con- 
nected end  to  end,  one  end  of  the  series  being  perma- 
nently  connected   to    one   wire    of   the   power   line.     Re- 

^MAMAAMA- 


H — mvr 


loX 


^ 

^ 


Fig.  14.     Diagram  showing  consumption  of  voltage  by  primary  of 
x-ray  transformer  and  series  resistance  for  a  particular  case. 

sistance  wire  is  made  of  some  special  material  of  con- 
siderably higher  resistance  for  the  same  diameter  and 
length  than  copper.  An  adjustable  contact  is  used  to  join 
one  transformer  terminal  to  any  desired  point  of  the 
rheostat  so  as  to  include  the  required  amount  of  resist- 
ance in  the  circuit.  Fig.  15  shows  the  essential  parts  of  a 
rheostat. 

The  usual  numbering  makes  the  power  increase  as  the 
control  lever  is  moved  over  to  higher  numbers.  A  good 
rheostat  should  be  of  substantial  construction,  well  ven- 
tilated, and  of  such  current  capacity  as  not  to  get  over- 
heated under  any  operating  conditions.     It  should  be  so 


X-RAY  PHYSICS 


51 


graded  as  to  give  30  to  70  ma.  on  a  4-inch  to  7-inch  gap  for 
radiographic  work  and  from  3  to  5  ma.  on  a  9  or  10-inch 

gap  for  treatment. 

The   use   of   a  rheo-  Transformer-^ 

stat  to  control  tube 
voltage  has  the  disad- 
vantage that  slight  va- 
riations in  tube  cur- 
rent result  in  serious 
changes  in  voltage.  To 
see  how  different  tube 
currents  cause  such 
enormously  different 
voltages  on  the  same 
control  setting,  let  us 
first  construct  a  table 
to    give    the    primary 

currents  corresponding  to  different  tube  currents.     Each 
primary  current  is  500  times  the  corresponding  secondary. 


Fig.  15.     Eheostat  construction   and 
connections. 


Secondary 

Current 

Primary  Current 

0  ma. 

0  amps. 

10 

5 

20 

10 

40 

20 

60 

30 

80 

40 

100 

50 

Assuming  the  setting  of  5  ohms  resistance,  let  us  see 
how  the  voltage  applied  at  the  transformer  varies  under 
different  loads.  The  voltage  consumed  in  the  rheostat 
is  V  ^  I R,  where  I  is  primary  current  and  R  is  constant 
at  5  ohms. 


52  U.  S.  ARMY  X-RAY  MANUAL 


Secondary 
Current 

Primary 
Current 

Voltage 

Consumed 

in 
Rheostat 

Voltage 

left  over 

to  apply 

at  primary 

Resulting 

secondary 

voltage 

0  ma. 

0  amp. 

0  V. 

220  V. 

110  kv. 

10 

5 

25 

195 

97 

20 

10 

50 

170 

85 

40 

20 

100 

120 

60 

60 

30 

150 

70 

35 

80 

40 

200 

20 

10 

100 

50 

250 

These  figures  are  represented  graphically  in  Fig.  16. 
This  results  in  the  theoretical  chart  line  corresponding  to 
operation  on  the  particular  rheostat  control  button  se- 
lected. For  simplicity,  no  account  has  been  taken  in  these 
figures  of  line  wire  resistance,  resistance  in  the  windings 
of  the  transformer,  ''magnetic  leakage,"  and  other  factors 
which  enter  to  a  greater  or  less  degree. 

The  voltage  "regulation"  under  various  loads  of  a 
rheostat  controlled  transformer  is  poor.  On  any  one  con- 
trol setting  the  voltage  will  fall  off  very  rapidly  with  an 
increase  in  current,  and  rise  rapidly  with  a  decrease.  In 
Fig.  16  at  60  kv.  and  40  ma.  an  increase  of  8  ma.,  due 
to  softening  of  a  gas  tube  during  exposure  or  to  fluctua- 
tion in  the  filament  temperature  of  a  Coolidge  tube,  will 
lower  the  voltage  10  kv.,  or  about  an  inch  of  spark  gap. 
The  loss  in  voltage  and  penetration  will  have  considerably 
more  influence  on  a  plate  than  the  increase  in  current. 
Also,  if  there  were  a  break  in  the  Coolidge  filament  line,  or 
polarity  were  wrong,  so  that  no  current  flowed  in  the  sec- 
ondary circuit  the  primary  voltage  would  rise  to  that  of  the 
line  with  considerable  likelihood  of  sparking  to  the  patient 
or  causing  damage  to  apparatus. 

Auto  Transformer. — To    secure    better    volta^re    main- 


X-RAY  PHYSICS 


53 


tenance  under  varying  loads  an  autotransformer  is  often 
used.  It  consists  of  a  continuous  coil  of  wire  wound  around 
an  iron  core  with  taps  taken  out  to  control  buttons  at 
proper  intervals,  as  shown  in  Fifr.  17.     If  alternating  cur- 

110 


WO 
30 
60 
10 
60 


m 


so 

40 
BO 
BO 
10 


^ 

"  k 

*  ^ 

jL          r~ 

\ 

Ql 

^  L 

^ 

W  ,     1                                                                                        •  p 

C 

^ 

J  L 

5   L^ 

% 

c 

"^  L 

* 

^ 

^        ^1                                                                                                                                                                           " 

"^  L 

1  . 

% 

^  L 

^  ^ 

^  . 

1                                                                         % 

c 

"  L 

*  . 

J  k_ 

1                                                                a 

s 

^  k 

I  \ 

^ 

■Am                                                                                                                s 

^\                                                         ^  r                                       — 

*  k 

^ . 

5 

K 

c 

'  k 

" 

5 

k  . 

-^                                            iC 

^  ^ 

* . 

^ 

.-_---».»--_».....      .- ....      » .    MM.. 9^ ....                1^ 

10    20   30   40    50    60 


70  60  eo  100 


Fig.  16.  Theoretical  chart  line  plotted  from  data  given  in  table 
on  page  52.  This  line  shows,  for  the  particular  machine  and  set- 
ting, the  voltage  at  which  various  currents  will  be  delivered. 

rent  be  applied  to  the  complete  winding  of  such  a  coil  there 
will  be  a  voltage  induced  in  any  part  of  the  winding,  bear- 
ing the  same  relation  to  the  applied  voltage  that  the  num- 
ber of  turns  of  this  part  of  the  winding  bears  to  the  num- 
ber of  turns  in  the  whole  coil.  It  is  essentially  the  same  as 
any  other  transformer,  except  that  primary  and  secondary 


54 


U.  S.  ARMY  X-RAY  MANUAL 


are  part  of  the  same  continuous  wire  rather  than  separate 
winding's,  and  its  action  depends  on  self-induction  in  a  sin- 
gle coil  rather  than  on  mutual  induction  between  two  coils. 
The  ratio  between  the  number  of  turns  in  the  primary  and 
secondary  circuits  is  changed  by  setting  the  control  lever 


Fig.  17.     Wiring  diagram  of  autotransformer.     Notice  dead  but- 
tons between  the  active  ones  which  are  numbered. 


on  the  various  buttons.  The  autotransformer  is  used  as  a 
control  device  to  reduce  the  line  voltage  to  that  which  is 
applied  to  the  x-ray  transformer  primary,  hence  it  is  a 
step-down  transformer  and  has  fewer  turns  in  the  sec- 
ondary circuit  than  in  the  primary.  As  the  control  handle 
is  moved  to  higher  readings,  more  turns  are  cut  into  the 
secondary   circuit   and   higher  voltage   is   applied   to   the 


X-RAY  PHYSICS  55 

primary  of  the  x-ray  transformer.  Blank  or  "dead"  but- 
tons arc  placed  between  adjacent  live  buttons,  which  differ 
from  each  other  by  a  few  volts,  to  prevent  a  short  circuit 
of  this  low  voltage  by  the  control  lever  being  in  contact 
with  two  live  buttons  at  one  time. 

The  autotransformer  is  more  suitable  than  a  variable  ^2**-2#-' 
ratio  step-down  transformer,  which  might  be  used,  since^<^^*i 
it  saves  wire  and  iron,  being  much  smaller  for  equivalent  ^22J^ 
capacity,  and  therefore  cheaper  to  build.    The  autotrans--fciy  .jrah. 
former  principle  cannot  be  appliejj^o  x-ray  a.nd  filament 
transformers  because  their  ratio  is  too  large  andjhg^pri- 
inary^nd  secondary ^ustjje  insulated  from_each^ther.  ,zUZo-? 

The  autotransformer,  like  an  ordinary  transformer,  is  j^jLUu^ 
very  efficient  and  does  not  change  electric  energy  into  ^^'^%jfj*^j^i7^. 
like  the  rheostat.  The  windings  are  of  large  copper  wir'^Xivtii^ 
with  low  ohmic  resistance.  "Wbenjncreased  current  is  ^^-^^2^^^ 
manded  from  an  autotransformer,  it  simply  draws  more  ^^^^^^^^^ 
current  from  the  supply  line  and  delivers  the  current  de-^^^-  *^ 

manded  with  very  little  drop  m  voltage.  .cMJU^CSii^  ^^-*  **^ 
When  incxeased  currenTis  demanded  in  thetube,  it  wiTl  "'^''^^'^^^ 
be  supplied  by  an  autotransformer  with,  far  less  voltage 
drqpthan  is  the  case  with  the  rheostat.  Fig.  18  shows  the 
behavior  of  the  two  devices  on  a  particular  machine.  Start- 
ing at  10  ma.  and  60  kv.,  and  raising  the  tube  current  on 
a  fixed  rheostat  setting,  gives  the  series  of  currents  and 
voltages  shown  by  the  line  AC ;  while  on  a  fi^xed  autotrans- 
former setting  we  have  the  line  AB.  Since  the  quantity  of 
radiation  (measured  photographically )  increases  as  the 
current  and  the  square  of  the  voltage,  we_may  compute  the 
relative  amount  of  radiation  regardless  of  penetration. 
Curve  DE  shows  the  rheostat  daliyery  down__aslowas_use- 
ful  rays  are  produced ;  DF  shows  the  delivery  on  the  auto- 
transformer up  to  60  ma. 

This  form  of  control  is  of  special  value  when  the  fila- 


56 


U.  S.  ARMY  X-RAY  MANUAL 


ment  current  of  a  Coolidge  tube  is  not  entirely  steady. 
Thus,  if  the  tube  current  in  the  case  cited  changed  from 
10  to  15  ma.,  with  a  rheostat  control,  the  radiation  would 
be  reduced  in  quantity  from  32  to  25  arbitrary  units  and 
also  would  be  much  less  penetrating;  while  with  the  auto- 
transformer  the  same  change  would  result  in  an  increase 


KV 


0         10     ZO     30    40     50     60     70     80     90     100 

Fig.  18.  Relation  of  x-ray  production  on  two  types  of  control. 
On  rheostat  control  we  have  ^C  as  the  voltage-current  line.  Voltage 
ordinates  at  the  left.  BE,  corresponding  x-radiation  quantity,  ord- 
inates  at  the  right.  AB,  autotransformer  chart  line.  BF,  corre- 
sponding quantity  line.     Quantity  in  arbitrary  units. 


in  quantity  from  32  to  50  units  very  slightly  less  pene- 
trating than  at  10  ma. 

"Inductance"  Taps. — Instead  of  controlling  completely 
by  variation  in  the  applied  voltage,  in  some  instances  the 
winding  ratio  of  the  x-ray  transformer  is  variable  by  a 
dial  switch  which  cuts  in  more  or  less  turns  of  the  trans- 
former primary.  The  lowest  ratio  of  step-up  corresponds 
to  the  complete  primary  and,  since  the  secondary  winding 


X-RAY  PHYSICS  57 

is  fixed,  to  cut  out  turns  of  the  primary  will  increase  the 
step-up  ratio  and  give  higher  secondary  voltage.  As  usual- 
ly applied,  the  machine  has  essentially  a  rheostat  control, 
with  rheostat  rather  than  autotransformer  characteristics, 
and  usually  more  taps  are  made  in  the  winding  than  serve 
a  useful  purpose. 

The  same  principle  is  conveniently  applied  in  transform- 
ers built  to  operate  on  either  220  or  110  volt  mains,  half 
as  many  primary'  turns  being  used  for  110  volts  as  for 
220.  The  bedside  unit  uses  this  principle  for  110  volt  a.c. 
and  the  lower  voltage  a.c.  obtained  from  the  rotary  con- 
verter. In  some  instances  the  primary  is  wound  in  two 
sections  which  are  connected  in  series  for  220  volts  and  in 
parallel  for  110  volts,  in  the  latter  case  giving  carrying 
capacity  for  the  heavy  primary  currents  as  well  as  the 
higher  step-up  ratio. 

Transformer  Chart. — A  proper  procedure  in  handling 
machine  and  tube  is  indispensable.  Such  a  method  should 
be  adopted  as  will 

1.  Save  time  and  tubes. 

2.  Eender  reproduction  of  results  possible. 

3.  Apply  to  all  machines. 

4.  Require  a  minimum  amount  of  instrument  reading 
when  operating. 

5.  Indicate  the  working  range  of  the  machine. 

The  working  spark  gap,  with  moderate  sized  blunt  points 
for  a  gap,  varies  from  about  3  inches  to  6  inches,  and 
currents  vary  from  5  to  100  milliamperes  in  fluoroscopic 
and  radiographic  work.  Any  possible  combinations  on 
the  machine,  giving  settings  outside  these  limits,  are 
practically  useless. 

On  any  transformer  outfit  find  first  a  5  ma.  6-inch  gap 
setting,  then  a  40  or  50  ma.  6-inch  gap  or  an  80  ma.  4-inch 
gap  setting.     Study  no  settings  outside  these  limits.     In 


58 


U.  S.  ARMY  X-RAY  MANUAXj 


Fig.  19  take  rheostat  setting  G  as  an  example.  Bead  the 
current  through  the  tube  when  a  6-inch  gap  just  fails  to 
break  (25  ma.).  Record  your  setting  and  the  current. 
Leaving  the  x-ray  transformer  control  unchanged  find  the 
tube  current  at  which  a  5-inch  gap  just  fails  to  break. 
Do  the  same  for  a  4-  and  for  a  3-inch  gap.  When  these 
readings  are  plotted  to  scale,  as  in  Fig.  19,  they  should 


/O      20     30     40     50     60     70     80      W     /OO 

HA. 

Fig.  19.  Partial  ''chart"  of  a  particular  machine  with  rheostat 
control.  Note  that  gap  change,  as  tube  current  increases,  is  very 
rapid.  On  G,  for  example,  we  have  a  6-inch  gap  at  25  ma.  and  only 
a  5-inch  gap  at  27.5  ma.  or  a  change  of  an  inch  for  each  2l^  ma. 
Compare  with  Fig.  20. 


fall  nearly  on  a  straight  line.  If  they  do  not  do  so,  repeat 
the  observations. 

So  long  as  the  power  supply  is  kept  at  the  voltage  pre- 
vailing when  this  chart  was  determined  the  coordinates  of 
a  line  give  all  the  currents  and  voltages  at  any  time  avail- 
able on  the  indicated  rheostat  setting.  H  gives  the  currents 
at  which  gaps  between  6  and  3  inches  are  broken  on  button 
H.  Fig.  20  shows  five  such  lines  for  a  particular  machine 
on  autotransformer  control. 

How  to  Use  the  Chart. — Using  chart,  Fig.  19,  one  needs 


X-RAY  PHYSICS 


59 


for  a  particular  case  20  ma.  at  a  4-inch  gap.  The  vertical 
line  through  20  cuts  the  line  marked  F  at  the  4-inch  gap. 
Hence  we  must  use  button  F.  Have  spark  gap  open  to 
seven  or  eight  inches  as  a  safety  valve  and  forget  it  en- 
tirely. ]\Iove  rheostat  lever  to  F,  look  at  your  milliamme- 
ter,  use  one  hand  on  transformer  primary  switch  and  the 
other  on  the  Coolidge  control.  Close  transformer  switch 
and  bring  filament  control  to  a  setting,  giving  20  milliam- 


/O      20     30     40     SO     60     70     60     90    '  100 

M.A 

Fig.  20.  Partial  ''chart"  of  the  same  transformer  using  auto- 
transformer  control.  Note  that  line  marked  P  shows  all  useful  cur- 
rents that  can  be  had  on  this  setting:  changing  from  5  ma.  to  50  ma. 
lowers  gap  from  5  to  3  inches. 


peres  tube  current;  there  is  no  need  of  testing  the  spark 
gap. 

Do  not  try  to  read  the  milliammeter  on  the  throw. 
Learn  to  start  and  set  your  machine  within  10  seconds. 
On  20  ma.  desired,  a  current  of  19  or  21  ma.  is  close  enough 
for  this  work. 

Using  chart,  Fig.  20,  for  45  ma.  at  a  4-inch  gap,  go  at 
once  to  R  and  proceed  as  before.  A  little  time  spent  in 
making  this  chart  and  in  using  it  will  reduce  time  lost 
and  failures.  Note  that  the  faster  the  spark  gap  falls  with 


60  U.  S.  ARMY  X-RAY  MANUAL 

increase  of  tube  current  the  more  accurately  must  the  fila- 
ment current  be  adjusted  and  maintained. 

Synchronous  Motors. — A  synchronous  motor  is  one  that 
makes  either  the  same  number  of  revolutions  per  minute  as 
the  generator  feeding  it  or  a  fixed  fraction  thereof.  Thus, 
if  fed  by  a  60  cycle  alternating  current,  there  are  7200 
alternations  per  minute.  One  alternation  is  produced  when- 
ever a  conductor  passes  one  pole  piece  of  the  generator. 
Thus,  a  60  cycle  current  from  an  eight-pole  machine  requires 

900     r.p.m      (revolu- 
I tions     per     minute) 

t     ' 


Main     cn 


— ,.  J^ 

Main 

CD 

IM 

1 


since  7200  =  8  x  900. 
For  a  four-pole  ma- 
ll^   chine  we  must  have 

1800  r.p.m.,  etc.  A 
four-pole  motor  must 
then  make  1800  r.p.m. 
for  synchronism  if  on 
such  a  circuit,  and  it 
must  not  make  1801 

Fig.  21.    Wiring  of  polarity  "switch.      Or  1799.     Since  t  h  e 

rectifier  for  a  60  cy- 
cle current  must  make  a  quarter-turn  each  1/120  of  a  sec- 
ond, the  motor  must  turn  at  1800  r.p.m.  It  must  be  ob- 
served that  such  a  motor  is  designed  for  a  given  fre- 
quency and  cannot  be  expected  to  work  on  one  greatly 
different  from  that  intended. 

Starting. — Many  motors  require  connection  to  a  special 
starting  device  in  order  to  bring  them  up  nearly  to  the 
required  speed  before  making  the  running  connection. 
Do  not  delay  too  long,  and  do  not  throw  over  the  switch 
too  quickly.  A  little  practice  will  enable  you  to  tell  by  the 
sound  of  the  machine  when  the  speed  is  about  right. 

Polarity  Indicator. — Some  machines  have  a  field  wind- 


X-RAY  PHYSICS 


61 


ing  which  ensures  the  same  terminal  polarity  each  time 
the  machine  is  started.  In  most  machines  there  is  as  much 
chance  of  a  given  terminal  starting  -|-  as  — .  Polarity  in- 
dicators are  often  used  to  show  which  way  the  rectifier 
comes  into  step.  Either  a  primary  reversing  switch,  Fig. 
21,  is  used  or  the  motor  switch  is  opened  for  an  instant 
and  again  closed,  thus  allowing  the  motor  to  drop  back  with 


mULfiTOR  SEGMENT 


jfEdiermcE 

Fig.  22.     Principle  of  polarity  indicator.    Note  resistance  in  series. 


the  chance  of  changing  polarity  of  the  high  tension  lines. 
These  indicators  are  devices  to  indicate  direction  of  cur- 
rent flow,  used  in  connection  with  a  small  low-tension  rec- 
tifier driven  by  the  motor.  In  Fig.  22  a  source  of  alter- 
ijating  current  is  obtained  from  the  primary  lines ;  C  is  the 
low  tension  rectifier,  or  commutator,  fastened  on  the  same 
shaft  as  the  high  tension  rectifier,  and  /  is  the  indicator. 
The  direction  of  the  rectified  current  through  the  indi- 
cator circuit  will  be  one  way  or  the  other,  depending  on 
how  the  two  rectifiers  happen  to  come  into  step.    The  indi- 


62 


U.  S.  ARMY  X-RAY  MANUAL 


cator  itself  consists  of  a  movable  coil  with  pointer  attached, 
working  against  a  hair-spring  in  a  permanent  magnetic 
field,  and  it  is  very  similar  in  construction  to  a  direct  cur- 
rent voltmeter  or  ammeter.  If  the  rectified  current  flows 
one  way  through  the  coil,  the  needle  will  be  deflected  to 
on  side;  if  the  current  flows  in  the  reverse  direction,  the 
needle  will  swing  to  the  opposite  side. 


Fig.  23.     Principle  of  rotary  converter  showing  two  positions  of 
active  coil  180°  apart,  armature  current  being  always  alternating. 


The  indicator  is  usually  of  low  resistance  with  an  auxil- 
iary resistance  unit  included  in  the  circuit  to  prevent  burn- 
out of  the  indicator  coil.  Never  connect  the  indicator  with- 
out this  resistance  in  circuit,  and  in  testing  to  flnd  the 
proper  connections  always  use  a  lamp  in  series  with  the 
indicator  to  prevent  burnout,  if  connection  is  accidentally 
made  to  too  high  voltage. 

Rotary  Converter. — If  the  line  supply  is  direct  current 
it  must  be  changed  into  alternating  by  means  of  a  rotary 


X-RAY  PHYSICS  63 

converter,  since  the  x-ray  transformer  will  operate  only 
when  its  primary  is  supplied  with  alternating  current. 
The  operation  of  the  converter  is  based  on  the  fact  that  the 
current  flowing  through  the  armature  of  a  direct-current 
motor  is  alternating.  To  simplify  explanation,  consider  the 
case  of  a  machine  having  two  field  poles  and  a  single  arma- 
ture coil.  At  the  left,  Fig.  23,  are  the  brushes  to  which  the 
direct  current  line  is  connected,  and  at  the  right  those  from 
which  the  alternating  current  is  drawn.  The  flow  of  cur- 
rent  through   the   armature   coil   in  the   direction  of  the 

^7? 7\ 7\ 2200.C 

/A y_A- L\...i54A.t 


TIME 


Fig.  24.     Eelation  between  d.c.  voltage  supplied  and  a.c.  voltage 
delivered. 

pointers  causes  rotation  of  the  coil  as  indicated,  owing  to 
the  reaction  with  the  magnetic  field  between  the  stationary 
pole  pieces.  When  the  coil  has  rotated  just  beyond  the  ver- 
tical plane  the  connection  of  the  rotating  commutator  seg- 
ments with  the  d.-c.  feed  brushes  is  reversed,  the  current 
through  the  armature  coil  is  reversed,  and  rotation  is  there- 
by made  to  continue.  Each  half  revolution  of  the  armature 
causes  a  reversal  of  current  through  the  armature  winding 
and  a  change  in  polarity  of  the  two  segments.  If,  now, 
these  segments  are  continuously  connected  to  the  same 
collector  brushes  by  means  of  slip  rings,  the  current  drawn 
from  these  brushes  will  be  alternating  current. 


64  U.  S.  ARMY  X-RAY  MANUAL 

The  direct-current  voltage  supplied  to  the  rotary  con- 
verter corresponds  to  the  peak  voltage  of  the  alternating 
current  wave,  and  the  effective  voltage  of  the  alternating 
current  is  only  about  70  per  cent  of  this,  Fig.  24.  Thus  a 
converter  operating  on  220  volts  d.c.  will  deliver  only  154 
volts  a.c.  and  if  220  volts  a.c.  are  required,  it  is  necessary 
to  step  up  by  means  of  a  special  transformer  or  autotrans- 
former.  Under  heavy  load  the  voltage  will  fall  considerably 
below  the  70  per  cent,  and  serious  difficulties  will  arise 
from  trying  to  use  a  rotary  converter  too  small  for  the 
demands  placed  upon  it. 

In  direct-current  x-ray  machines  the  rotary  converter 
drives  the  rectifying  device.  In  this  case,  the  machine  al- 
ways starts  up  with  the  same  high  tension  polarity,  and  a 
polarity  indicator  or  polarity  switch  is  unnecessary.  If 
polarity  is  wrong  permanently,  interchange  the  primary 
lead  wires  at  the  transformer  or  reverse  the  tube  in  the 
stand. 

In  using  a  rotary  converter,  one  should  remember  that 
all  the  power  used  passes  into  the  rotary  through  the  d.-c. 
brushes,  and  all  used  by  the  x-ray  transformer  passes  out 
from  the  slip  rings.  In  the  a.-e.  machine  the  transformer 
power  does  not  pass  through  the  motor,  so  that  greater 
care  of  brushes,  etc.,  is  needed  in  the  d.-c.  machine. 

A  considerable  proportion  of  failures  of  rotaries  is  due 
to  the  breakdown  of  insulation  at  the  connection  of  the 
armature  wires  to  the  slip  rings.  ' '  The  Care  of  Motors ' '  on 
page  84  applies  also  to  rotary  converters.  Protection 
should  be  made  against  high  tension  surges  by  connecting 
an  incandescent  lamp  across  the  a.-c.  end,  as  is  done  to 
protect  a  transformer,  Fig.  13. 

Rectifier. — Two  forms  of  rotating  circuit  changers  are 
in  common  use,  the  cross-arm  type  and  disc  type.  Both  are 
run  by  a  synchronous  motor,  and  they  must  be  correctly 


X-RAY  PHYSICS 


65 


placed  relative  to  the  motor  armature  if  efficient  delivery 
is  to  be  secured.  Fig  25  shows  the  current  path  for  the 
four-arm  type,  Fig.  26  for  the  two-arm,  and  Fig.  27  for 
the  disc  type. 

In  Fig.  25  when  the  right  hand  terminal  of  the  trans- 
former is  -,  the  flow  of  negative  charge  or  of  electrons  is 
from  A-B-tuhe-C-D.  If  the  spindle  turns  90°  while  the 
polarity  of  the  transformer  is  reversed,  electrons  flow  from 


— H V/  I  t 


7 


Rnr 


u. 


E  A 


/ 


u. 


H 


Tr. 


Fig.  25.  Secondary  circuit  of 
^nook  machine.  Cross-bar  type 
pectifier — four  arms. 


Fig.  26.  Second  circuit  Waite 
&  Bartlett  machine — cross-arm 
type — two  arms. 


E-F-iube-G-H.  In  both  cases  the  current  takes  the  same 
direction  through  the  tube. 

The  disc  type  is  shown  in  Fig.  27.  PQ  and  RS  are  two 
conducting  sectors  fastened  to  an  insulating  disc  turned  by 
the  motor. 

Flow  is  A-B-tuhe-C-D  in  one  case  and  a  quarter  turn 
connects  D  to  B  and  C  to  A.  Meanwhile  the  transformer 
has  reversed  so  that  electrons  pass  from  D-B-tube-C-A. 

In  Fig.  25  the  cross-arm  machine,  E  and  A,  C  and  F,  B 
and  G  must  be  well  insulated  by  barriers,  or  else  the  shaft 
must  be  unduly  long.  In  the  disc  machine  the  diameter 


66 


U.  S.  ARMY  X-RAY  MANUAL 


must  be  large  enough  to  insure  insulation  between  the  shaft 
and  the  rim  and  also  to  avoid  establishing  an  arc  between 
the  fixed  sectors  along  the  edge  of  the  disc. 

Sparking"  Troubles. — Dust  and  moisture  may  impair  the 
insulation  of  the  barriers  or  disc.     Keep  them  clean  and 
wipe  with  a  cloth  slightly  moistened  with  kerosene. 
The  cross-arm  type  must  be  well  insulated  where  the 

arms  pass  through  the 
shaft.  If  a  break  occurs 
there,  it  is  not  possible  to 
patch  it  up.  Get  a  new 
cross-arm. 

Noise. — If  a  disc  is  out 
of  balance  or  if  the  bear- 
ings are  worn  by  lack  of 
lubrication  a  machine  will 
be  noisy.  Be  sure  to  keep 
bearings  well  oiled.  Do 
not  accept  a  machine  poor- 
ly balanced. 

Inverse. — Inverse  shows 
by  fluorescent  rings  back 
of  the  target  in  a  gas  tube  and  by  sparks  across  gap  on 
low  power  setting  on  Coolidge  tube.  It  is  caused  by  recti- 
fier out  of  position.  It  is  assumed  that  the  maker  will 
mark  the  shaft  of  the  cross-arm  type  or  the  disc  in  the 
other  class  with  reference  to  the  motor  shaft  so  that  one 
can  see  if  slip  has  taken  place  and  adjust  to  the  proper 
position.  If  this  has  not  been  done,  readjust  so  that  the 
current  is  a  maximum  on  a  low  power  setting  and  with 
the  tube  kept  constant.  This  is  fairly  easy  with  a  Coolidge 
tube.  One  accustomed  to  the  appearance  of  the  arcs  at 
the  rectifier  terminals  can  set  fairly  accurately  by  obser- 
vation. 


Fig.  27.     Secondary   circuit   for 
disc  type  of  rectifier. 


X-RAY  PHYSICS 


67 


Electro  Magnet  and  Solenoid. — Surrounding  a  wire 
while  it  is  carrying  an  electric  current  there  is  always  a 
magnetic  field  which  will  deflect  a  compass  needle  placed 
near  it  into  a  position  as  shown  in  Fig.  28.  If  now  the 
wire  be  wound  into  a  coil  the  magnetic  action  formerly 
distributed  along  the  length  of  the  wire  is  concentrated  in 
the  center  of  the  coil,  and  if  a  piece  of  iron  be  inserted  as 
a  core  the  intensitj^  of  the  field  will  be  still  further  in- 
creased since  the  iron  is  much  more  permeable  to  magne- 

\\r 


<!Z:' 


<^-> 


•  •^i 


U  U  U  U 


'"zr* 


B 


Fig.  28.  Eelation  between  an  electric  current  and  its  resulting 
magnetic  field,  (a)  Cross  section  of  conductor  with  compass  needle 
in  field,  (b)  Straight  portion  of  a  conductor  showing  current  and 
field,  (c)  Magnet  coil  with  iron  core.  Greater  strength  than  the 
same  coil  without  iron  core. 

tism  than  air.  The  coil  is  a  magnet  only  while  current  is 
actually  flowing  and  its  magnetic  strength  is  greater  the 
more  turns  of  wire  and  the  greater  the  current,  and  de- 
pends also  on  the  dimensions  and  quality  of  the  iron  core 
and  the  design  of  the  magnet  as  a  whole.  If  the  core  is 
fixed  and  the  magnetic  action  attracts  an  iron  armature, 
as  in  some  remote  control  switches,  it  is  called  simply  an 
electro-magnet,  whereas  if  the  winding  is  hollow  and  by 
its  magnetism  sucks  an  iron  plunger  into  the  coil,  as  in 
the  throttle  control  of  the  portable  unit  engine  and  cer- 
tain remote  control  switches,  it  is  called  a  solenoid.  An 


68  U.  S,  ARMY  X-RAY  MANUAL 

electro  magnetic  winding  should  never  be  connected  on  a 
voltage  for  which  it  was  not  designed,  and  a  winding  made 
for  a.c.  or  d.c.  must  never  be  connected  to  the  other  type 
of  current  supply,  as  is  explained  in  the  next  section. 

Choke  Coil. — If  an  alternating  current  be  applied  to  an 
electro  magnet  there  will  be  a  choking  effect  due  to  the 
slow  magnetizing  of  the  core  and  the  rapid  alternation 
of  the  current.  Less  current  will  flow  than  if  a  corre- 
sponding voltage  of  direct  current  be  applied,  and  the  dif- 
ference will  depend  on  the  properties  of  the  magnet  and 
the  frequency  of  alternation.  Never  expect  a  magnet  de- 
signed for  d.c.  to  operate  satisfactorily  on  a.c,  for  it  will 
not  let  pass  sufficient  current;  and  never  connect  an  a.-c. 
winding  to  d.-c.  lines,  since  so  much  current  will  flow  as 
to  most  likely  burn  out  the  coil  immediately. 

The  choke  coil  is  quite  generally  used  instead  of  a 
rheostat  as  a  means  of  control  for  the  Coolidge  filament 
transformer.  Variation  is  secured  by  moving  a  piece  of  iron 
in  or  out  of  the  field,  the  more  iron  in  the  field  the  more 
choking  effect  and  the  dimmer  the  filament,  and  the  less 
iron  the  brighter  the  filament.  Gradation  of  control  is  com- 
plete and  there  are  no  sliding  contacts  to  cause  trouble. 

Protection  against  Surge. — The  insulation  of  the  appa- 
ratus in  the  primary  circuit  is  sufficient  for  220  volts,  but 
not  for  high  tension.  If  a  sudden  impulse  or  surge  of  elec- 
tricity is  set  up  in  the  primary  circuit,  due  to  a  ground 
or  short  circuit  of  the  secondary,  or  a  spark  back  to  the 
primary,  the  voltage  in  the  circuit  may  amount  to  many 
times  what  it  normally  is. 

Most  of  the  apparatus  in  the  primary  circuit  is  induc- 
tively wound  (electromagnetic  coils  with  an  iron  core) 
and  offers  so  much  objection  to  the  passage  of  a  sudden 
surge  that  the  path  of  least  resistance  may  be  through 
the  insulation  of  the  coils  rather  than  through  the  com- 


X-RAY  PHYSICS  69 

plete  winding.  "When  the  insulation  is  punctured  by  the 
momentary  pulse  of  high  tension  and  a  spark  established, 
the  low  voltage  is  able  to  maintain  this  spark  and  build 
up  a  heavy  arc,  resulting  in  a  burnout. 

Protection  against  surges  in  the  primary  can  be  secured 
by  connecting  in  shunt  with  the  main  transformer  and 
motor  a  protective  resistance,  as  shown  in  Fig.  13.  This 
resistance  is  so  high  that  it  normally  lets  pass  an  insig- 
nificant amount  of  current,  but  in  case  of  a  surge  the 
current  will  go  through  the  resistance  rather  than  break 
down  the  insulation,  and  the  apparatus  is  protected. 

The  protective  resistance  may  be  in  the  form  of  a  car- 
bon rod,  an  open  winding  of  fine  resistance  wire,  a  resist- 
ance wire  baked  into  an  enameled  porcelain  shell,  or 
simplest  of  all,  an  ordinary  incandescent  lamp.  If  the  more 
elaborate  devices  become  broken  and  cannot  be  replaced,  a 
lamp  should  be  substituted  rather  than  leave  the  equip- 
ment unprotected.  If  the  lamps  at  hand  are  not  of  suf- 
ficient voltage,  they  can  be  connected  in  series ;  two  110-volt 
bulbs  in  series  are  equivalent  to  a  220-volt  bulb. 

Remote  Control  Switch. — Machines  are  frequently 
equipped  with  remote  control  switches  or  contactors  which 
serve  to  make  and  break  the  heavy  primary  currents  and  to 
permit  the  use  of  a  small,  convenient  operating  switch.  The 
operating  push  button  or  other  device  makes  and  breaks  a 
small  current  in  an  auxiliary  circuit,  which  is  sufficient  only 
to  operate  the  magnetic  switch.  AYhen  the  auxiliary  cir- 
cuit is  closed,  current  passes  through  the  magnet  of  the 
remote  control  switch  and  attracts  an  iron  armature,  there- 
by making  contact  and  closing  the  main  primary  circuit. 
When  the  auxiliary  circuit  is  opened  the  magnet  ceases  to 
attract  the  armature  and  a  spring  or  gravity  opens  the 
contacts  in  the  main  primary. 

The  timing  elements  of  most  timers  are  delicate  devices 


70  U.  S.  ARMY  X-RAY  MANUAL 

and  not  able  to  make  and  break  the  heavy  main  primary 
current.  They  should  be  connected  always  in  the  auxil- 
iary circuit  of  a  remote  control  switch,  where  the  current 
is  light  and  will  not  cause  damage,  and  they  should  never 
be  inserted  directly  in  the  main  primary  circuit. 

Line  Wiring-. — The  line  for  x-ray  installations  should 
receive  more  careful  attention  than  has  usually  been  given 
to  such  important  work. 

The  primary  or  low  tension  wiring  should  contain  enough 
copper  to  insure  that  there  will  be  no  considerable  voltage 
drop  on  the  line  even  when  the  heaviest  work  is  done.  If  a 
line  from  a  supply  transformer  or  a  generator  has  a  resist- 
ance of  say  .3  ohms,  and  one  draws  50  amperes,  a  loss  of 
.3  X  50  =  15  volts  would  result.  If  the  original  voltage 
was  100,  the  total  available  at  the  x-ray  transformer  would 
be  85  volts.  On  220  volt  operation  this  is  not  so  serious, 
but  more  reliable  operation  will  be  attained  if  the  wire  is 
such  that  at  the  highest  primary  current  the  line  drop  does 
not  exceed  3  per  cent. 

When  a.-c.  lines  are  used,  the  transformer  from  which 
power  is  drawn  should  be  of  ample  capacity,  and  on  d.c. 
the  generator  should  have  a  capacity  exceeding  any  esti- 
mated demand.  Connecting  a  10  kw.  x-ray  transformer  to 
a  5  kw.  line  transformer  is  poor  business.  Fuses  or  circuit 
breakers  should  be  conveniently  placed,  and  all  care  should 
be  exercised  to  avoid  short  circuiting  or  grounding  the  lines. 

The  following  table  shows  the  loss  in  voltage  of  a 
primary  line  for  50  and  100  amperes  low  tension  current, 
on  the  assumption  of  a  run  of  100  feet  between  an  x-ray 
transformer  and  the  power  transformer,  giving  200  feet  of 
line.  The  terminal  voltage  to  be  taken  by  primary  and  con- 
trol is  the  difference  between  the  line  voltage  and  the  loss. 
Thus,  a  machine  drawing  100  amperes  for  a  short  exposure 
on  a  220  volt  circuit,  using  No.  10  wire,  will  have  220  — 


X-RAY  PHYSICS  71 

19.9,  or  about  200  volts  available.  On  110  volt  operation, 
110  —  19.9  ^  90  volts,  making  a  very  decided  percentage 
drop.  For  this  reason,  machines  using  a  large  primary  cur- 
rent are  unsuited  for  110  volt  operation  if  rapid  work  is 
required. 

Volts  lost  Volts  lost 

200  ft.  50  Amp.      200  ft.  100  Amp. 
J78  1.5 

.98  1.96 

1.24  2.4 

1.56  3.1 

1.97  3.9 

2.48  4.9 

3.13  6.2 

3.94  7.8 

4.97  9.9 

6.27"  12.5 

7.91  15.8 

9.97  19.9 

To  compute  the  size  of  wire  needed,  one  must  know:  (a) 
the  maximum  primary  current  in  the  x-ray  transformer; 
(b)  the  distance  from  the  supply  transformer  (or  genera- 
tor)  to  the  x-ray  transformer. 

The  loss  in  voltage  due  to  line  resistance  is  given  by 
the  product  of  current  in  amperes  hy  resistance  in  ohms 
of  line  wire  per  foot,  hy  length  of  supply  wires  in  feet. 
Thus,  on  a  220  volt  line,  if  a  drop  of  6  volts  is  permis- 
sible, the  line  being  200  feet  long  and  the  maximum 
current  60  amperes,  then 

60  x  200  X  Resistance  per  foot  =  6  volts 

6 

Resistance  per  foot  = — ,  =  .0005  ohms. 

60  X  200 


Ohms 

No. 

per  ft. 

00 

.0000778 

0 

.000098 

1 

.000124 

2 

.000156 

3 

.000197 

4 

.000248 

5 

.000313 

6 

.000394 

7 

.000497 

8 

.000627 

9 

.000791 

10 

.000997 

72  U.  S.  AR]\IY  X-RAY  MANUAL 

The  smallest  permissible  wire  then  is  "No.  7."  Better 
use  a  wire  considerably  larger  to  insure  the  best  opera- 
tion. 

Hig:h  Tension  Wiring. — In  the  use  of  high  power  ma- 
chines, much  greater  care  should  be  taken  in  high  tension 
construction  than  is  generally  the  case.  Three  points  should 
be  carefully  considered.  These  are :  First,  safety  of  the 
patient  and  operator;  second,  prevention  of  loss  by  leak- 
age ;  third,  avoidance  of  puncture  of  tubes. 

While  one  might  get  a  very  unpleasant  jolt  from  an 
induction  coil,  yet  danger  to  life  is  slight  as  compared 
with  transformers  of  like  voltage.  In  general,  a  main- 
tained voltage  of  500  through  vital  portions  of  the  body 
is  dangerous  if  a  current  of  100  ma.  or  more  can  be  de- 
livered. A  static  machine,  an  induction  coil,  or  a  con- 
denser may  give  a  high  initial  voltage  with  a  hrief  rush 
of  current  upon  contact  or  grounding;  this  is  disagreeable 
but  usually  harmless.  In  a  power  transformer  which 
maintains  voltage,  the  current  continues,  with  possible 
fatal  results.  In  most,  if  not  all,  installations  the  middle 
of  the  secondary  coil  of  the  transformer  is  connected  to 
the  iron  case  or  to  the  ' '  earth ' ' ;  the  earth  is  such  a  large 
reservoir  that  its  electrical  condition  may  be  regarded 
as  constant.  The  ''ground"  need  not,  and  in  fact  should 
not,  be  completed  by  an  actual  metallic  connection  of 
transformer  case  to  a  water  or  gas  pipe.  Thus,  when 
working  at  60  kv.  between  the  tube  terminals,  the  volt- 
age between  the  -\-  line  and  the  earth  is  +  30  kv.,  and 
between  the  —  line  to  earth  —  30  kv. 

This  divides  the  insulation  strain  on  the  transformer 
and  reduces  danger  of  sparking  to  the  stand.  If  one  ter- 
minal of  the  transformer  were  grounded,  the  full  voltage 
would  tend  to  pass  current  from  the  other  line  to  any- 
thing connected  to  the  earth.    Thus,  there  would  be  a  ten- 


X-RAY  PHYSICS 


73 


inch  spark  length  to  stand,  floor,  water,  and  gas  pipes,  etc. 
AVhen  treating  at  a  ten-inch  gap  the  strain  is  then  double 
that  in  the  other  connection,  but  the  line  to  the  grounded 
side  of  the  transformer  is  safe  to  touch.  When  using  metal 
stands,  tables,  and  protecting  screens  with  the  metal  screens 
hetiveen  the  tube  and  the  patient,  they  should  be  well 
grounded.    The  patient  is  then  free  from  induced  ''static" 


FltnMBNT 
TRfiNeFORMEH 


Section  at  'A' 


Fig.  29.  Arrangement  for  constant  resistance  between  filament 
transformer  and  Coolidge  filament.  Wire  may  be  used  instead  of 
brass  tube  in  the  same  way. 


and  from  any  discharge  that  may  occur  between  the  parts 
of  the  outfit.  When  the  patient  is  between  the  tube  and  the 
grounded  metal,  there  is  always  more  danger  to  the  patient, 
and  corresponding  care  must  be  used. 

Aside  from  the  difficulty  of  preventing  spark  discharges 
and  arcs,  it  is  of  great  importance  to  prevent  leakage  be- 
tween all  parts  having  a  high  potential  difference.  This 
leakage  is  due  to  high  electric  stress,  rendering  the  air 
conducting  and  giving  rise  to  ''corona."  Also,  many  good 
insulators  when  clean  and  dry  become  conducting  when 


74 


U.  S.  ARMY  X-RAY  MANUAL 


dusty  and  moist.    High  tension  wires  mounted  on  ordinary 
wood  or  on  glass  may  be  expected  to  leak  badly. 

Surface  leakage  is  less  on  hard  rubber  and  micanite 
than  on  glass.  Wiping  insulating  surfaces  with  a  cloth 
slightly  moistened  with  kerosene  will  often  greatly  reduce 
leakage  over  the  surface. 

Corona  loss  is  decreased  by  reducing  the  electric  stress 
between  the  conductor  and  the  surrounding  air.     This  is 

accomplished  by  avoid- 
ing points,  sharp  edges, 
and  close  proximity  of 
conductors  of  high  po- 
tential difference.  High 
potential  overhead  lines 
should  be  from  24  to  30 
or  more  inches  apart. 
All  sharp  points  and 
corners  should  be  avoid- 
ed and  small  wires,  es- 
pecially if  cloth  insu- 
lated, should  not  be 
used.  Gutta  percha  cov- 
ered wire  without  braid- 
ed covering  is  useful  where  a  flexible  conductor  is  needed. 
For  rigid  wiring  and  overhead  lines,  metal  tubing  not  less 
than  half  inch  external  diameter  should  be  used.  This 
may  be  mounted  by  insulating  rods  attached  to  the  ceiling, 
or  as  shown  in  Fig.  29. 

The  same  design  can  be  easily  adapted  to  inter-con- 
necting rooms  by  mounting  the  tubing  in  the  center  of 
a  large  micanite  or  porcelain  tube  and  filling  the  space 
with  a  good  insulating  wax.  The  insulating  tube  should 
be  extended  6  to  8  inches  from  the  wall.  The  rings 
for  tube  connection  may  carry  reels  if  desired. 


/T\ 


Fig.  30.  The  path  of  negative 
charge  from  line  through  spark  gap, 
tube  and  milliammeter. 


X-RAY  PHYSICS  75 

While  line  leakage  of  moderate  amount  may  be  toler- 
ated in  fluoroscopic  or  radiographic  work,  it  may  be  of 
great  importance  in  treatment.  A  milliannneter  measures 
not  alone  the  tube  current  but  all  leakage  heijond  the  in- 
strument itself.  Corona  between  wires,  spark  gap  corona 
and  surface  leakage  together  may  give  an  error  of  two 
or  three  hundred  per  cent.  AVe  may  avoid  this  (1)  by 
proper  design,  (2)  by  alivaijs  connecting  the  milliammeter 
beyond  the  spark  gap  as  shown  in  Fig.  30.  (3)  AVhere  any 
doubt  arises  check  by  testing  with  a  second  milliammeter 
connected  directly  to  the  tube. 

Tracing  Circuits. — The  modern  transformer  x-ray  ma- 
chine is  rarely  characterized  by  simplicity  of  wiring  or 
accessibility  of  connections.  In  case  of  trouble,  or  where 
one  must  connect  or  set  up  the  machine  without  expert 
aid,  it  is  w^ell  to  learn  to  trace  the  circuits  and  to  test  out 
for  breaks,  etc. 

While  to  one  unaccustomed  to  do  this,  it  seems  very 
difficult,  a  few  suggestions  may  help.  There  are  only  two 
main  current  paths  from  one  supply  line  through  the  ap- 
paratus to  the  other  line — the  motor  circuit  and  the  trans- 
former circuit.  In  tracing  either  circuit,  follow^  a  com- 
plete metallic  path  from  one  supply  line  through  the  motor 
or  transformer  back  to  the  other  supply  line.  Where  paths 
divide,  they  must  come  together  again  further  on,  and  one 
must  avoid  simply  chasing  around  some  loop.  The  main 
circuit  in  outline  on  all  resistance  controlled  machines  is 
shown  in  Fig.  31. 

Where  no  attempt  to  bring  the  motor  contact  into  cor- 
rect phase  is  made,  a  reversing  switch  is  provided.  Fig.  32. 
which  changes  polarity  of  transformer  without  disturbing 
the  motor  circuit.  There  may  be  a  special  switch  to  be 
operated  by  a  small  current  through  a  magnet.  Fig.  33. 
A  timer  connection  may  be  added,  as  in  Fig.  34.     Several 


76 


U.  S.  ARMY  X-RAY  MANUAL 


F     M 


Rh. 


Fig.  31.     Simple  primary  circuit,  rheostat  control. 


Fig.  32.     Addition  of  reversing  switch  (polarity  changer). 


Fig.  33.     Magnetic  control-switch  added. 


Fig.  34.     Time' switch  and  foot  switch  added. 


X-RAY  PHYSICS 


77 


Fig.  35.     Multiple  taps   ("Inductance  taps")    added. 


Fig.   36.     Autotransformer   instead   of   multiple  primary   taps. 


A.  Autotransformer. 

C.  Coolidge   filament   transformer 

F.  Fuses. 

F.S.     Foot  Switch. 

F.S.S.S.  Foot  switch  safety  switch. 

G.  Ground  to  case  of  transformer. 
I.  Inductance  taps. 

K.V.    Kilovolt  meter. 
M.  Main  switch. 
Mot.     Motor, 


O.  Operating  switch. 
Pol.  Polarity  changer. 
Pol.I.    Polarity  indicator. 
Pr.  Primary  of  transformer. 
Prot.    Protective  resistance. 
R.  Remote  control  contactor. 
Eeg.    Filament  regulator. 
Ees.    Resistance. 
Rh.  Rheostat. 
T.  Timer, 


78  U.  S.  ARMY  X-RAY  MANUAL 

taps  (inductances)  may  be  brought  out  from  the  primary 
winding,  Fig.  35.  There  may  be  a  polarity  indicator  to 
show  the  way  to  place  the  reversing  switch  for  a  given 
tube  connection.  An  autotransformer  may  be  used  as 
the  control  device,  Fig.  36.  The  fundamental  wiring 
scheme  of  all  base  hospital  machines  likely  to  be  used  is 
shown  in  Fig.  37.  There  are  a  considerable  number  of  dif- 
ferences between  the  various  machines  but  they  all  con- 
form more  or  less  to  the  same  general  scheme.  Different 
models  put  out  by  the  same  manufacturer  may  be  no  more 
alike  than  the  different  makes.  Whatever  machine  be 
used,  to  become  familiar  with  the  wiring  will  help  to  quickly 
overcome  difficulties  when  they  arise. 

Locating  Trouble. — Troubles  in  x-ray  apparatus  may  be 
divided  into  two  groups:     (a)  mechanical;  (b)  electrical. 

Under  mechanical,  we  may  have  worn  bearings,  worn 
or  broken  brushes,  slip  of  rectifier  on  shaft;  warping  of 
wood,  thus  throwing  shaft  out  of  alignment.  Care  in 
oiling  and  keeping  apparatus  clean  and  dry  will  prevent 
most  of  these. 

Under  electrical  troubles  we  have:  (a)  Improper  con- 
nections; (b)  break  in  conducting  line;  (c)  loose  connec- 
tions;  (d)   failure  of  insulation. 

To  avoid  (a)  all  wires  removed  from  their  connections 
should  be  labeled  as  well  as  the  binding  posts,  etc.,  from 
which  they  were  disconnected.  Serious  damage  may  be 
done  if  one  attempts  to  operate  with  improper  connections. 

To  find  breaks,  close  switches  and  use  test  lamps,  as 
directed  in  the  following  pages.  When  the  lamp  lights 
on  connecting  two  points  between  which  the  resistance 
should  be  low,  there  must  be  a  poor  connection  or  a  break. 

Loose  contacts  are  likely  to  cause  irregular  or  intermit- 
tent action.     Failure  of  insulation  may  cause  current  to 


X-RAY  PHYSICS 


79 


m 


(um^ 


4^    o 


L~ 


!-  ■--   I- 

o  —  o 
:^        &( 


o    2    S" 


l!i 

■*^  -~  'C 
rt  ^  »^ 

J  o  c 

"5     O  ^ 

—    S   S 

is  ^ 

^■^  i 

g  c  = 


S'fi 


o 


-  -^  <^ 

;;       O  -1-3 

?■  ^  g 

rt  o  f-i 

S I  >; 

3  s 

& 


cc  f^ 


2    «    !=! 


80  U.  S.  ARMY  X-RAY  MANUAL 

pass  between  two  wires  without  going  through  the  proper 
path. 

If  the  fuse  in  any  part  of  the  circuit  blows  when  only 
moderate  power  is  used,  open  all  switches  and  look  for 
a  short  circuit;  and  if  none  is  found  insert  a  new  fuse 
and  test  out  on  low  power  before  attempting  to  continue 
work.  Beware  of  the  high  tension  line  and  terminals 
when  hunting  trouble  on  the  primary  or  motor  circuit. 


6 

Fig.  38.     Use  of  a  lamp  in  trouble  hunting. 

Primary  Circuit. — ^When  a  machine  which  has  been 
operating  fails  to  work,  there  must  be  trouble  in  either 
the  supply  or  some  part  of  the  circuit  insulation  or  wiring. 
The  low  tension  side  may  be  easiest  tested  by  using  an 
ordinary  incandescent  lamp  of  suitable  voltage.  Start  back 
of  the  fuses  on  the  main  line,  having  motor  and  transformer 
switches  open.    Fig.  38. 

Touch  lamp  terminal  wires  (bared  ends)  to  bare  wire 
at  1  and  2.  If  the  line  is  "alive,"  a  220  volt  lamp  will 
light  up  to  half  brightness.  Do  the  same  for  2  and  3. 
Connect  1  to  5,  and  if  lamp  fails  to  light,  fuse  B  is  burned 
out.  Or,  if  switches  are  closed  and  the  lamp  lights  when 
connected  to  the  opposite  ends  of  a  fuse,  as  2  to  5,  the 


X-RAY  PHYSICS  81 

fuse  must  be  burned  out.  Try  2  to  4  and  2  to  6 ;  if  all 
these  connections  give  equal  brightness  to  the  filament, 
the  trouble  must  be  further  along. 

Close  motor  starting  switch,  and  if  motor  does  not  start 
connect  lamp  across  motor  fuses  one  at  a  time.  If  a  fuse 
is  intact,  it  has  so  low  a  resistance  that  current  will  not 
pass  through  the  lamp ;  if  broken,  the  full  line  voltage  ap- 
pears at  the  break,  and  the  lamp  will  light. 

Finally,  connect  across  the  motor  terminals,  and  if  the 
lamp  lights  fully  the  trouble  is  inside  the  motor. 

Follow  the  same  general  procedure  in  testing  the  trans- 
former circuit,  but  use  great  care  to  keep  away  fro*in 
the  high  tension  terminals;  also,  be  sure  to  set  rheostat 
at  lowest  power. 

If  the  lamp  lights  across  the  low  tension  terminals  and 
no  spark  can  be  driven  across  a  short  gap  between  the 
secondary  terminals,  the  trouble  is  inside  the  transformer 
and  the  chance  of  its  repair  by  an  operator  is  slight.  If 
a  break  is  near  the  terminals,  it  may  sometimes  be  located 
and  repaired ;  otherwise  it  must  be  sent  to  a  manufacturer. 

Secondary  Circuit. — Outside  of  a  break  in  the  second- 
ary coil  or  an  arc  to  the  case,  the  most  common  trouble  in 
the  secondary  line  is  a  complete  or  partial  short  circuit. 
This  may  occur  in  various  ways : 

1.  In  a  cross  arm  machine,  the  insulation  may  break 
down  between  the  cross  conductor  and  the  rectifier  shaft. 

2.  In  a  disc  machine,  the  disc  may  be  dirty  or  car- 
bonized, ''shorting"  around  the  periphery  or  to  the  motor 
shaft. 

3.  A  high  tension  line  may  be  in  contact  with  the  tube 
stand,  a  wall  containing  metal  lath,  the  floor,  etc. 

The  latter  may,  of  course,  be  remedied  at  once  by  the 
operator. 


82 


U.  S.  ARMY  X-RAY  MANUAL 


In  case  of  rectifier  trouble,  a  Coolidge  tube  may  be  run 
directly  on  the  transformer,  provided  low  spark  gap  and 
current  is  used  so  that  the  target  does  not  get  hot.  For 
fluoroscopic  work  there  is  no  trouble  in  doing  this,  but 
for  radiography  time  must  be  allowed  between  exposures 
for  the  target  to  cool. 

Care  of  Tubes. — All  tubes  are  fragile  and  may  easily  be 
d-amaged  by  fracture.  A  warm  tube  must  not  be  placed  on 
a  cold  support.  Keep  tubes  free  from  dust  and  moisture. 
Do   not   allow   either  high   tension   wire   to   come   within 

Reducer 
Raiser         _ 


Fig.  39.     Diagram   showing  softening  and  raising  connections  on 
Snook  hydrogen  tube, 

five  or  six  inches  of  the  glass  bulb.  Always  heat  the  fila- 
ment of  the  Coolidge  tube  before  attempting  to  pass  cur- 
rent through  it.  Preserve  cases  or  frames  in  which  tubes 
are  received  for  the  return  of  punctured  tubes  or  those 
requiring  repumping.  Use  great  care  in  softening  gas 
tubes.  Never  soften  a  gas-containing  tube  with  rheostat 
set  for  heavy  radiography ;  use  low  power.  If  a  tube  is  too 
soft,  the  rays  emitted  will  not  pass  through  the  flesh.  Bet- 
ter take  more  time  and  soften  stepwise,  testing  after  each 
short  passage  of  current  through  the  softener. 

To  soften  the  Snook  hydrogen  tube,  pass  through  the 
reducer  about  15  ma.  flve  or  ten  seconds  at  a  time.     Re- 


X-RAY  PHYSICS  83 

peat  if  necessary.  Do  not  use  more  current ;  use  more  time. 
Always  maintain  polarity,  as  shown  in  Fig.  39. 
To  harden  the  tube,  pass  through  the  raiser  about  25  ma. 
(never  more  than  30  ma.)  twenty  seconds  at  a  time.  If 
the  tube  is  excessively  soft,  disconnect  spiral  temporarily 
from  -|-  terminal  of  raiser.  Connect  anode  wire  to  4" 
terminal  of  raiser  and  cathode  to  —  terminal  of  raiser. 
Run  three  minutes  with  22  to  25  ma.  Repeat  if  neces- 
sary. Replace  spiral.  Regulate  tube  before  making  ex- 
posure. It  should  test  out  at  2-inch  gap  and  about  5  ma. 
The  tube  tends  to  harden  a  trifle  during  the  first  exposure 
when  the  tube  is  cold.  To  compensate,  introduce  a  little 
more  gas.  Operate  at  40  ma.  for  a  medium  focus  tube. 
It  will  give  much  more  service  than  at  45  to  50  ma.  A 
sharp  focus  should  be  limited  to  20  ma.  and  the  time  of 
exposure  doubled.  Use  a  broad  focus  tube  for  extremely 
fast  exposures  in  making  stomach  and  intestinal  plates. 

When  a  tube  is  in  operation,  the  heat  developed  at  the 
target  is  measured  by  the  current  x  voltage.  If  this 
heat  is  produced  at  such  a  rate  that  it  cannot  be  dissi- 
pated by  conduction  and  radiation,  the  metal  at  the  focal 
spot  may  be  vaporized  or  melted  and  the  tube  ruined  very 
quickly. 

It  is  rarely  necessary  to  do  so-called  flash  or  instanta- 
neous work,  and  it  can  only  be  done  at  high  tube  cost.  Prop- 
erly used,  a  tube  is  capable  of  a  large  amount  of  work. 

Do  not  use  intermittent  excitation  during  an  exposure. 
In  heavy  work,  if  60  ma.  for  four  seconds  overheats  the 
tube  at  the  gap  needed,  many  operators  close  the  switch  for 
four  separate  seconds  with  three  intervals  of  a  second  or 
more.  The  patient  must  remain  at  rest  for  seven  seconds. 
The  same  exposure  may  be  secured  with  40  ma.  continu- 
ously delivered  for  six  seconds.  In  the  latter  case  the 
danger  of  pitting  or  cracking  the  target  is  less  and  the 


84  U.  S.  ARMY  X-RAY  MANUAL 

part  need  be  held  immobile  for  less  time.  This  intermit- 
tent method  has  been  suggested  to  overcome  the  tendency 
for  voltage  drop  on  heating  gas  tubes  while  in  operation, 
but  the  allowable  interval  is  too  short  to  do  much  good. 

Care  of  Motors. — 1.  All  motors  need  oil  at  periods  de- 
pending on  the  amount  of  use.  Failure  to  oil  may  cause 
the  bearings  to  wear  enough  to  allow  the  armature  to  rub 
on  the  field  supports  and  ruin  the  motor.  Follow  the 
maker's  instructions,  if  any  are  given.  Do  not  use  too 
light  an  oil.  An  oil  like  3  in  1  is  good  for  sewing  ma- 
chines, but  must  not  be  used  on  power  motors.  Use  real 
machine  oil. 

2.  Most,  if  not  all,  motors  used  on  x-ray  machines  have 
either  slip  rings  or  commutators,  or  both.  Bearing  on  these 
are  carbon  or  other  conducting  brushes.  As  the  tension  is 
low,  these  must  have  a  good,  even  contact.  Springs  are 
provided  to  secure  this,  and  if  these  break  or  get  out 
of  adjustment  there  will  be  either  intermittent  contact  or 
none.  The  motor  then  either  fails  to  start  or  it  sparks  at 
these  bad  contact  points  and  corrodes  the  metal  rings  or 
commutator  bars.  If  only  slightly  injured,  they  may  be 
smoothed  down  by  00  sandpaper  (not  emery  cloth),  lubri- 
cated slightly  with  paraffin  or  light  oil  and  rubbed  off  with 
a  clean  cloth.  New  brushes  should  be  inserted  before  any 
serious  trouble  occurs.  Be  sure  and  put  them  in  right, 
noting  carefully  how  the  old  ones  were  placed. 

3.  Many  motors  have  two  sets  of  connections,  one 
for  starting,  the  other  for  running.  Usually  a  double  throw 
switch  is  used  and  marked  for  the  purpose.  Don't  close 
on  the  running  side  and  wait  for  something  to  happen. 
Don't  throw  over  too  quickly.  Don't  leave  switch  on  start- 
ing position. 

4.  Keep  motor  clean  and  in  as  dry  a  place  as  circum- 
stances permit. 


X-RAY  PHYSICS  85 

5.  If  the  motor  fails  to  start,  open  the  starting  switch 
and  test  the  fuse  on  the  motor  circuit;  also  be  sure  the 
line  is  ''alive."  If  power  is  on  and  the  fuse  is  intact,  go 
carefully  over  the  wiring  to  the  motor,  examine  brushes, 
look  at  all  external  wires,  and  if  no  break  is  found  it  is 
fairly  probable  that  some  internal  trouble  has  developed 
requiring  technical  motor  knowledge  for  repair. 

6.  Be  very  sure  not  to  connect  a  motor  on  a  line  for 
which  it  was  not  designed, — as  an  a.-c.  motor  on  a  d.-c. 
line ;  or  a  220  volt  motor  on  a  110  volt  line,  or  the  reverse ; 
or  an  a,-c.  motor  designed  for  60  cycles  on  a  40  cycle 
line,  etc. 

7.  If  an  a.-c.  motor  fails  to  run  at  the  right  speed,  do 
no  try  to  operate  tubes  with  it. 

8.  It  is  w^ell  to  have  the  field  and  the  armature  of  an 
x-ray  motor  protected  from  small  sparks  due  to  transient 
surges.  Ordinary  incandescent  lamps  in  shunt  serve  very 
well  for  this  purpose.  Most  machines  have  such  protection, 
using  either  lamps,  or  special  high  resistances,  or  con- 
densers. 

Care  of  Transformers. — The  attention  of  every  roent- 
genologist should  be  called  to  the  danger  to  the  x-ray  trans- 
former arising  from  carelessness  in  operation.  There  are 
certain  things  which  should  never  be  done  even  though  they 
might  be  done  many  times  without  damage. 

1.  Never  operate  at  high  applied  voltage  when  the 
tube  is  taking  no  current,  or  on  an  open  circuit,  especially 
with  rheostat  control  on  high  buttons.  In  this  case  the 
effective  gap  measuring  the  strain  upon  the  insulation  may 
be  very  much  in  excess  of  what  is  needed  in  practice. 

2.  High  tension  wires  should  not  come  in  contact  with 
or  close  to  steam  or  gas  pipes,  electric  service  wires,  metal 
ceilings  or  walls,  metal  tube  stand,  or  the  x-ray  cabinet. 
Keep  them  away  from  things,  where  they  belong.     When 


86  U.  S.  ARMY  X-RAY  MANUAL 

a  discharge  occurs  from  one  high  tension  line  to  the  earth 
the  danger  to  the  insulation  of  the  transformer  may  be 
greater  than  in  the  case  of  a  discharge  between  the  two 
lines. 

3.  In  all  cases  when  starting  up  the  machine  test  out 
for  proper  operation  on  low  power  and  especially  be  care- 
ful not  to  attempt  operation  of  any  kind  of  tube  with 
rectified  current  of  wrong  polarity.  If,  on  moderate  fila- 
ment current  and  a  low  power  setting,  no  current  is  drawn 
through  a  Coolidge  tube,  reverse  the  polarity  and  again 
test.  After  a  machine  is  once  up  to  synchronism  it  will  very 
rarely  change  polarity  while  running,  but  it  may  do  so 
in  case  of  a  momentary  interruption  of  service  or  unsatis- 
factory line  conditions.  It  is  wise,  whenever  lights  operat- 
ing on  the  same  power  circuit  as  the  x-ray  apparatus  be- 
come dim  or  are  temporarily  extinguished,  to  throw  the 
machine  to  low  power  and  again  test  for  polarity. 

4.  Look  to  the  oil  level  about  every  two  months  and 
record  the  date  on  a  tag  attached  to  the  transformer.  If 
the  level  is  low,  add  more  oil  until  all  the  coils  are  properly 
covered.  Be  sure  to  use  transformer  oil  that  has  not  been 
open  and  exposed  to  dirt  and  moisture.  Wipe  oil  and 
dirt  off  the  top  of  the  transformer  case. 

5.  Be  sure  that  the  transformer  is  adequately  pro- 
tected against  surges  by  a  suitable  type  of  protective  re- 
sistance. 

Care  of  Batteries. — The  only  type  of  battery  likely  to  be 
met  in  x-ray  practice  is  the  storage  battery.  This  is  some- 
times used  for  portable  coil  work,  and  quite  often  to  light 
the  Coolidge  filament.  Each  separate  cell  of  a  storage 
battery  adds  about  two  volts  to  the  line.  For  any  given 
voltage,  then,  half  as  many  cells  must  be  used  as  volts 
are  needed.  This  voltage  is  independent  of  the  size  of 
the   cells.      A   storage   cell  does   not   store   electricity;   it 


X-RAY  PHYSICS  87 

uses  electricity  to  cause  a  chemical  change  in  its  plates, 
and  when  it  is  discharged  this  chemical  change  is  reversed 
and  electric  current  flows  from  the  cell.  The  amount  of 
chemical  change  on  proper  charge  is  in  proportion  to  the 
charging  current  and  the  time  of  flow,  and  is  estimated 
in  ampere-hours. 

Thus,  a  10  ampere-hour  battery  will  deliver  ten  amperes 
for  one  hour,  1  ampere  for  ten  hours,  i/o  an  ampere  for 
twenty  hours,  etc.  Too  rapid  charge  or  discharge  should 
be  avoided  because  of  damaging  the  battery. 

The  storage  battery  consists  of  two  sets  of  plates,  each 
containing  a  salt  of  lead  held  in  some  sort  of  small  lead 
pockets,  the  whole  being  immersed  in  a  solution  of  sul- 
phuric acid.  In  a  single  cell,  all  the  positive  plates  are 
joined  together,  likewise  all  the  negative,  and  these  sets 
must  not  be  in  contact.  The  negative  of  one  cell  must 
be  joined  to  the  positive  of  an  adjacent  one,  leaving  one 
-f-  and  one  —  for  external  connection.  The  ampere- 
hour  capacity  depends  on  the  area  of  -|-  and  —  plates  per 
cell. 

The  following  are  the  main  points  to  be  kept  in  mind 
when  using  storage  batteries: 

1.  They  must  be  charged  on  direct  current. 

2.  The  charging  rate  given  by  the  maker  should  not 
be  exceeded. 

3.  The  discharge  rate  allowable  should  not  be  exceeded. 

4.  Loss  of  electrolyte  by  evaporation  must  be  replaced 
by  adding  distilled  water,  rain  water,  or  as  pure  water  as 
can  be  had. 

5.  Loss  of  electrolyte  by  accidental  spilling  must  be 
replaced  by  adding  an  acid  solution  of  the  proper  den- 
sity. 

6.  In  making  up  an  acid  solution,  never  pour  water  into 
the  acid,  but  pour  acid  slowly  into  the  water. 


88 


U.  S.  ARMY  X-RAY  MANUAL 


7.  Never  let  the  solution  get  so  low  as  to  leave  a  por- 
tion of  the  plates  bare. 

8.  Do  not  overcharge,  nor  discharge  after  the  voltage 
falls  below  1.8  volts  per  cell. 

9.  Do  not  let  the  battery  freeze. 

10.  Do  not  let  the  battery  stand  idle  for  long  periods. 
If  it  must  be  laid  up,  charge  it  fully  and  draw  off  the 
solution.  For  short  periods,  put  a  high  resistance  across 
its  terminals  and  let  it  slowly  discharge,  and  charge  it 
up  again  at  intervals. 


SAAAAAAAAMA 


B 


B 


Fig.  40.     Storage  battery  charging:  BB— two  cells  in  series;   V- 
voltmeter:   A — ammeter. 


11.  If  overheated  by  too  high  current  passing  m  or  out, 
the  active  material  is  likely  to  crumble  and  fall  to  the 
bottom  of  the  cell  and  cause  a  short  circuit,  whereby  the 
battery  discharges  internally. 

12.  The  discharge  voltage  falls  quite  rapidl}^  after  a 
battery  is  first  charged,  then  more  slowly  until  nearly 
discharged,  then  rapidly.  "When  used  on  a  Coolidge  fila- 
ment, which  requires  about  four  amperes,  it  is  well  to  pass 
twelve  or  fifteen  amperes  through  a  suitable  resistance  for 
three  or  four  minutes  to  bring  the  voltage  down  to  the 
steady  state  the  first  time  it  is  used  after  charging. 


X-RAY  PHYSICS  89 

13.  A  small  voltmeter  is  very  useful  in  charging  a  bat- 
tery, and  a  suitable  resistance  to  bring  the  line  voltage  down 
to  that  required  in  charging  should  always  be  at  hand. 
Either  a  voltmeter  or  a  test  for  acid  density  may  be  used 
to  indicate  full  charge. 

14.  Do  not  fail  to  disconnect  the  charging  line  before 
using  on  a  Coolidge  tube. 

15.  Storage  cell  terminals  are  almost  sure  to  corrode; 
scrape  clean  when  connecting. 

The  charging  connections  are  shown  in  Fig.  40.  If 
the  battery  has  any  charge,  it  will  deflect  the  voltmeter 
in  the  same  direction  when  discharging  as  when  charg- 
ing. Connect  the  voltmeter  in  the  right  way  before  start- 
ing to  charge,  and  it  will  tell  you  whether  you  have  con- 
nected to  the  charging  line  correctly.  The  ammeter  may  be 
omitted  if  one  knows  that  the  charging  current  is  neither 
too  large  nor  too  small. 

Emergency  Provisions. — In  military  x-ray  work  it  is  of 
the  utmost  importance  that  apparatus  be  kept  going  at  all 
times  to  meet  the  demands  that  are  placed  upon  it.  The 
roentgenologist  must  keep  in  mind  the  human  lives  de- 
pendent on  him,  and  he  must  make  every  effort  to  repair, 
improvise,  or  do  without  whatever  piece  of  apparatus  may 
fail  in  the  rush  of  work.  There  may  be  loss  of  time  in 
securing  replacement  parts  or  repair  assistance,  and  during 
this  delay  the  plant  must  be  maintained  in  operation.  The 
following  are  some  suggestions  for  emergencies. 

Polarity  Indicator. — This  piece  of  apparatus  may  be 
classed  as  a  luxury,  and  in  case  repair  cannot  readily  be 
made  no  interruption  of  sarvice  is  warranted.  With  a  gas 
tube,  polarity  is  readily  shown  by  the  appearance  of  the 
tube.  Correct  polarity  results  in  a  uniform  color  and 
inverse  in  a  series  of  rings.  With  a  Coolidge  tube  the 
milliammeter  serves  as  a  guide,  for  no  current  will  flow^ 


90  U.  S.  ARMY  X-RAY  MANUAL 

through  the  tube  in  the  inverse  direction.  If  the  meter 
registers,  the  polarity  is  right.  Always  test  on  low  power 
to  avoid  puncturing  the  tube.  Spark  gap  may  be  used 
as  an  index  if  the  meter  also  has  failed,  since  on  the  same 
control  setting  the  gap  will  be  greater  when  the  tube 
is  not  taking  current  than  when  it  is. 

In  case  of  burnout  of  the  resistance,  sometimes  in- 
cluded in  the  polarity  indicator  circuit,  an  incandescent 
lamp  may  often  be  substituted.  Never  attempt  to  connect 
up  without  the  resistance. 

MilUammeter. — In  working  without  a  milliammeter  the 
appearance  of  a  Coolidge  tube  gives  no  idea  as  to  the 
amount  of  radiation  produced.  If  the  machine  is  on  a 
steady  power  line  the  transformer  chart  may  be  used  as 
an  accurate  means  of  obtaining  a  setting  of  the  machine. 
Suppose  a  5-inch  gap  and  40  ma.  is  desired,  refer  to  the 
chart  and  find  which  control  button  must  be  used.  Then, 
instead  of  using  the  chart  in  the  customary  way,  set  the 
gap  for  5  inches  and  vary  the  filament  temperature  until 
the  spark  is  barely  able  to  break  the  gap.  The  milliam- 
perage  will  now  be  right — 40  ma. 

The  appearance  of  a  gas  tube  is  somewhat  of  a  guide  to 
tube  current,  but  if  an  accurate  chart  has  been  made  of 
the  machine  it  is  safer  to  refer  to  that.  At  what  appears  to 
to  be  a  working  setting,  measure  the  spark  gap.  Then 
see  what  current  corresponds  to  this  gap  on  the  control 
button  used. 

In  working  under  uncertain  conditions,  he  sure  that  the 
spark  gap  is  as  high  as  it  should  he.  A  difference  in  tube 
current  will  affect  only  the  quantity  of  radiation;  a  dif- 
ference in  voltage  not  only  changes  the  quantity  but  the 
penetration  as  well. 

Timer. — If  the  timer  fails,  exposures  may  be  made  ac- 
cording to  the  second  hand  of  a  watch  or  by  counting 


X-RAY  PHYSICS  91 

seconds.  *'One  thousand  one,  one  thousand  two,  one  thou- 
sand three,"  etc.,  is  a  convenient  method,  and  a  little  prac- 
tice will  enable  one  to  keep  close  pace  with  a  stop  watch. 

Remote  Control. — In  case  of  failure  of  the  remote  con- 
trol magnet  coil  or  another  device  in  its  circuit  the  custo- 
mary operating  switch  will  be  of  no  service.  It  is  pos- 
sible, in  some  instances,  to  wire  around  the  remote  control 
switch,  or  block  it  closed,  and  operate  from  an  auxiliary 
switch  in  the  main  circuit,  such  as  a  pole-changing  switch. 
Of  course,  care  must  be  taken  to  always  close  the  switch  the 
right  ivay,  otherwise  there  is  great  danger  of  tube  breakage 
and  sparking  to  the  patient  on  inverse  polarity.  Or,  in 
some  cases  it  would  be  more  convenient  to  operate  by  hold- 
ing the  remote  control  switch  closed  with  a  stick  during 
the  exposure. 

Protective  Resistance. — If  the  shunt  resistance  or  con- 
densers protecting  against  surges  become  broken  or  un- 
serviceable, do  not  leave  the  circuits  unprotected,  since  a 
more  vital  element  may  be  damaged.  An  incandescent 
lamp  of  proper  size  and  voltage  (usually  220  Y,  16  candle 
power,  carbon  filament)  connected  in  shunt  as  shown  in 
Fig.  13  is  very  good  protection. 

Motor  or  Rectifier. — In  case  of  breakage  of  the  rectifier 
or  burnout  of  the  synchronous  motor,  work  may  still  be 
done  by  working  on  low  power  and  letting  the  Coolidge 
tube  do  its  own  rectifying.  (If  the  rotary  converter  fails 
on  a  direct  current  installation  and  alternating  current  is 
not  available,  nothing  can  ordinarily  be  done.)  Set  the 
rectifier  in  position  so  there  will  be  a  minimum  of  spark- 
ing distance  to  the  collector  brushes,  or  wire  across  these 
gaps.  Leave  the  motor  switch  open,  or  in  case  it  must 
be  closed  to  get  current  through  the  main  primary  and 
filament  primary  circuits,  disconnect  the  lead  wires  to  the 
motor  and  tape  the  ends  to  prevent  short  circuit.     Then, 


92  U.  S.  ARMY  X-RAY  MANUAL 

starting  an  low  power,  set  the  tube  for  a  5-incli  working  gap 
and  5  ma.  All  Coolidge  tubes  will  operate  self-rectifying 
so  long  as  the  target  does  not  become  hot  enough  to  emit 
an  appreciable  number  of  electrons.  Do  not  work  at 
more  than  5  ma.  and  do  not  let  the  target  heat  to  redness, 
or  the  tube  will  no  longer  rectify,  and  will  very  soon  be 
ruined. 

Spark  gap  is  not  a  reliable  guide  to  working  voltage  in 
a  self-rectifying  tube,  since  the  inverse  voltage  is  higher 
than  the  working  voltage.  (See  page  37.)  The  excess 
over  working  voltage  depends  on  the  resistances  in  circuit 
and  the  type  of  control.  To  secure  a  setting  of  5-inch 
working  gap  and  5  ma.,  refer  to  the  chart  of  the  machine 
and  set  to  5  ma.  on  the  proper  control  button.  Check  by 
seeing  that  the  spark  gap  is  approximately  that  at  which 
the  chart  line  crosses  the  vertical  axis  of  the  chart.  Be 
sure  that  the  working  voltage  is  what  it  should  be  to  give 
rays  of  adequate  penetration.  Do  all  radiographic  work 
either  by  giving  increased  time  or  by  using  intensifying 
screens  and  exposing  as  with  the  bedside  unit. 

Autotransformer  or  Rheostat. — On  many  machines  hav- 
ing combined  control,  a  failure  of  one  of  these  elements 
would  merely  necessitate  leaving  it  out  of  circuit  and 
controlling  by  the  other.  Broken  wires  or  burned-out 
coils  in  a  rheostat  are  easily  wired  across,  but  a  failure 
•in  an  autotransformer  is  a  much  more  difficult  proposi- 
tion. In  case  it  is  necessary  to  improvise  a  complete 
new  control,  this  may  be  done  by  building  a  water  rheo- 
stat. 

Fill  a  large  wooden  pail  with  water  and  drop  into  it  a 
lead  or  iron  plate  of  about  60  square  inches  area  with  wire 
attached,  for  an  electrode,  as  in  Fig.  41.  Suspend  securely, 
and  so  its  immersion  may  be  definitely  controlled,  a  smaller 


X-RAY  PHYSICS 


93 


snLT 

SOLUTION 


piece  of  metal  as  the  other  electrode.  Immerse  it  slightly 
to  correspond  to  the  lowest  power  setting  desired.  Test 
it  out,  and  add  ordinary  salt  slowly,  making  sure  that  it  is 
all  dissolved,  and  testing  at  intervals  until  the  desired 
low-power  setting  is  reached.  Pure  water  is  a  very  poor 
conductor  of  electricity,  and  the  addition  of  salt  lowers 
the  resistance  of  the  solution  to  the  desired  amount.  Hiorh- 
er  powers  will  be  secured  by  immersing  the  upper  elec- 
trode deeper  in  the  so-     _^ ^ 

T     ,.  ,     ,  X     CONTROL  ELECTfr'ODE 

lution  and  loAver  pow- 
ers by  withdraw- 
ing  it. 

It  may  be  noted  that 
in  case  of  failure  of 
both  rheostat  and  auto- 
transformer  on  220  volt 
machines,  as  a  general 
rule  we  may  secure  rea- 
sonable operation  by 
applying  110  volt  serv- 
ice directly  to  the  220 
volt  connections  on  the 

transformer.  Then  select,  when  using  the  Coolidge  tube, 
that  current  which  will  give  a.  5-inch  gap  and  modify 
exposures  if  the  current  is  greater  or  less  than  that  usually 
employed. 

Fuses. — In  case  the  supply  of  plug  or  cartridge  fuses 
runs  out  never  ivire  across  the  cut-out  block  with  copper 
wire.  Have  an  ample  supply  of  10  ampere  fuse  wire  on 
hand  and  include  the  proper  amount  of  this  in  the  cir- 
cuit. To  fuse  for  30  amperes  use  3  strands  in  parallel, 
for  50  amperes  use  5  strands,  and  so  on,  Fig.  42.  For  less 
than  ten  amperes  the  wire  may  be  whittled  down  to  smaller 
cross  section.     The  leng-th  of  the  fuse  wire  does  not  alter 


LE/9D  PLfiTE 


Fig.  41.  Emergency  rheostat  for 
control  of  primary  of  x-ray  trans- 
former. 


94 


U.  S.  ARMY  X-RAY  MANUAL 


the  current  at  which  it  will  blow,  nor  does  the  voltage 
of  the  line  on  which  it  is  used. 

The  above  suggestions  cover  most  of  the  cases  that  are 
likely  to  occur.  The  resourcefulness  of  the  roentgenologist 
is  relied  upon  to  cover  the  others  and  to  keep  his  plant 
in  operation  so  long  as  he  has  electric  power,  a  transformer, 
and  a  tube.  With  these  three  essentials  and  a  little  in- 
genuity he  should  be  expected  to  generate  x-rays  and  do 
creditable  work  in  an  emergency  rather  than  shut  down 
and  wait  for  assistance. 

Ordering  Supplies  and  Repairs. — Much  delay  and  incon- 


I] 


•( 

• 

•( 

h 

I 


\oa. 


20  R.        dOR,        40  R,        50  R 


Fig.  42.     Method  of  using  10  ampere  fuse  wire  to  secure  capacity 
desired.    It  may  be  soldered  to  the  brass  ends  of  the  burned  out  fuses. 

venience  will  be  avoided  if  care  is  taken  to  state  explicitly 
just  what  is  wanted  and  the  exact  quantity.  The  work 
of  the  supply  depot  must  be  done  by  people  who  cannot 
be  familiar  with  every  minute  detail  of  x-ray  equipment, 
and  mind  readers  are  scarce. 

When  ordering  a  machine  specify: 

1.  Type  of  current,  a.c.  or  d.c. 

2.  The  frequency  of  cycles,  if  a.c. 

3.  The  voltage. 

4.  The  power  available  in  kw. 

5.  Gauge  and  length  of  wire  needed  to  connect  up. 

6.  If  d.c,  always  specify  a  rotary  converter  and  the 
d.-c.  voltage. 

7.  Be  sure  to   state  that  the  motor,  transformer  and 


X-RAY  PHYSICS  95 

Coolidge  filament  transformer  when  used  on  154  volts  or 
70  volts  a.c.  from  a  rotary  must  operate  properly. 

Thus — 220-volt-a.c.-60  cj^cle-lO  kw — specifies  a  definite 
type  of  machine. 

In  ordering  repair  parts  state  the  name  of  the  apparatus, 
the  maker,  if  known,  and  either  give  a  drawing  or  such 
an  exact  description  or  name  as  to  identify  the  piece  re- 
quired. Sometimes  one  may  return  a  broken  or  defective 
part  as  a  complete  identification. 

In  case  of  supplies  be  sure  to  give  the  amount  and  any 
other  information  that  will  make  your  needs  clearly  un- 
derstood. Thus  an  order  for  "an  x-ray  screen"  is  mean- 
ingless ;  one  for  a  "10  x  10  inch  Patterson  fluoroscopic 
x-ray  screen,  mounted  with  lead  glass,"  is  definite. 

Never  fail  to  give  complete  address  to  which  goods  are 
to  be  forwarded. 

No  small  part  of  what  we  protest  against  as  "red  tape" 
is  made  necessary  by  failure  of  individuals  to  convey  a 
clear  idea  of  what  they  desire. 

When  possible  confine  your  requests  to  those  articles 
specified  in  the  supply  tables. 

Induction  Coils. — It  sometimes  becomes  necessary  to 
work  for  a  time,  at  least,  with  an  induction  coil.  While 
not  often  used  in  this  country  one  must  be  prepared  to 
use  it  if  need  be  abroad. 

Coil  Characteristics. — A  good  induction  coil  should  be 
able  to  give  a  heavy  discharge  at  a  voltage  high  enough 
to  break  a  10-  or  12-inch  gap. 

Under  no  circumstances  must  a  coil  be  operated  at  high 
power  long  enough  to  heat  the  insulation,  as  the. insulat- 
ing power  is  much  reduced  at  high  temperatures.  Each 
coil  has  its  own  characteristics  which  determine  its  best 
working  conditions.  These  characteristics  depend  on  the 
primary   and   secondary  resistances,   on   the   amount   and 


96  U.  S.  ARMY  X-RAY  MANUAL 

quality  of  iron  in  the  core,  on  the  number  of  turns  in 
the  coil,  and  on  the  mode  of  winding. 

The  most  undesirable  feature  in  coil  operation  for  x- 
ray  work  is  the  unavoidable  inverse  which  must  be  mini- 
mized in  the  use  of  the  ordinary  tube.  The  amount  of 
inverse  depends  on  the  coil,  the  interrupter  and  the  tube. 
A  coil  having  a  considerable  number  of  primary  turns 
and  but  little  ''magnetic  leakage"  gives  less  trouble  with 
inverse  than  other  types. 

The  direction  of  secondary  current  while  the  primary 
is  increasing  is  opposite  to  that  during  a  decrease  of 
primary  current.  Generally  it  is  possible  to  reduce  pri- 
mary current  at  a 
greater  rate  than  that 
at  which  it  can  be  built 
up.  Hence  the  "break" 
voltage  is  usually  high- 
er than  that  at ' '  make. ' ' 

The   current   of   higher 

Fig.  43.    Valve  tube.  i,  •  r?  i    •      xi, 

voltage  IS  useiul  m  the 

tube,  but  the  inverse  is  not  only  ineffective  for  ray  pro- 
duction but  is  a  source  of  positive  injury  to  the  ordinary 
tube.  If  the  make  current  could  be  caused  to  rise  slowly 
enough,  the  resulting  secondary  voltage  would  not  force 
current  through  the  tube.  In  practice  this  is  not  pos- 
sible, although  the  voltage  giving  ''inverse"  may  be  very 
much  smaller  than  that  giving  "direct." 

Valve  Tubes. — In  order  to  reduce  "inverse"  as  far  as 
possible,  various  unsymmetrical  tubes,  Fig.  43,  have  been 
devised ;  these  offer  much  greater  resistance  to  discharge  in 
one  direction  than  the  other.  Such  valve  tubes  are  often 
supplemented  by  a  series  of  small  spark  gaps  which  are 
readily  broken  down  by  the  ' '  direct, ' '  but  not  by  the  lower 
voltage  "inverse."     These  devices  all  reduce  the  energy 


X-RAY  PHYSICS 


97 


available  for  x-ray  production.  Fig.  44  shows  a  tube 
designed  to  indicate  the  presence  of  inverse.  If  there  is 
no  inverse,  only  one  of  the  metal  terminals  at  the  gap 


cB^^ 


A 


Fig.  44.     Vacuum  tube  oscilloscope. 


^P, 


will  glow.     If  both  glow  to  the  same  extent,  inverse  cur- 
rent is  present. 

Fig.  45  shows  the  wiring  diagram  for  a  coil  with  mer- 


■RHEOSTflT 


MERCURy 
iNTERRUPTEn 


Fig.  45,     Complete  connection  for  the  operation  of  tube  with  in- 
duction coil  and  mercury  interrupter. 

cury  interrupter,  condenser,  oscilloscope,  valve  tube,  and 
series  spark  gap.  Note  that  the  milliammeter  is  next  to 
the  tube. 

When  the  spark  gap  is  placed  between  the  meter  and 
the  tube,  leakage  across  the  gap  may  make  the  reading 


98 


U.  S.  ARMY  X-RAY  IMANUAL 


much  above  the  current  actually  passed  through  the  tube. 
Interrupters. — The  secondary  voltage  of  an  induction 
coil  is  the  result  of  change  of  current  in  the  primary.  It 
is  evident  that  we  cannot  have  the  primary  current  grow 
indefinitely,  so  we  must  allow  it  to  decrease  and  increase 
alternately.  The  value  of  the  secondary  voltage  for  a 
given  coil  depends  entirely  on  the  rate  at  which  the  primary 
current  is  changed.  Thus,  if  a  current  of  80  amperes 
should  be  reduced  to  0  amperes  in  .02  seconds,  the  current 

nc. 

+  - 


il 


jfjkSwiTCH 


Pt.       Rb 
Interrupter 

Fig.  46.     Wiring  for  induction  coil  with  electrolytic  interrupter. 


has  changed  at  a  mean  rate  of  4000  amperes  per  second. 
If  it  required  .04  seconds  for  the  same  change,  the  rate 
is  2000  amperes  per  second.  The  mean  secondary  voltage 
is  twice  as  great  in  the  former  case  as  in  the  latter. 

As  induction  coils  are  intended  to  operate  on  an  in- 
terrupted direct  current,  some  device  must  be  used  to  open 
and  close  the  circuit.  The  early  interrupters  were  of 
the  vibrating  hammer  type,  but  these  have  largely  been 
superseded  by  others  much  better  adapted  to  x-ray  work, 
-They  are  still  used  on  small  outfits  where  large  power 
is  not  drawn. 


X-RAY  PHYSICS 


99 


The  Wehnelt  Interrupter. — The  AVelmelt  interrupter 
consists  of  a  lead  and  a  platinum  electrode  immersed  in  a 
solution  of  sulphuric  acid.  The  amount  of  platinum  ex- 
posed to  the  solution  is  usually  variable  at  will.  When 
connected  as  shown  in  Fig.  46,  the  application  of  sufficient 
voltage  will  result  in  the  formation  of  a  non-conducting 
layer  between  the  solution  and  the  platinum,  thus  inter- 
rupting current  flow.  The  layer  is  very  quickly  dissipated, 
reestablishing  current  onlj^  to  be  again  formed,  etc.    "When 

To  Motor 


VTTT^."^ 


Fig.  47.      Centrifugal  jet  mercury  interrupter. 

only  a  small  amount  of  platinum  surface  is  exposed,  the 
number  of  interruptions  per  second  is  high  and  the  cur- 
rent is  small.  Greater  immersion  lowers  the  number  of 
interruptions  and  draws  more  current. 

Operating  Notes. — 1.  The  solution  should  contain  30  to 
35  per  cent  pure  sulphuric  acid.  In  mixing,  be  sure  to 
add  small  amounts  of  acid  to  water,  allowing  the  mixture  to 
cool  after  each  amount  is  added.  Never  pour  water  into 
the  acid. 

2.  Do  not  use  a  condenser,  as  is  done  with  the  mechani- 
cal interrupter. 


100 


U.  S.  ARMY  X-RAY  MANUAL 


3.  If  your  point  or  points  are  adjustable,  use  little  or 
no  resistance  in  series  with  coil  and  interrupter  on  a 
110  volt  circuit. 

4.  Your  coil  may  not  have  the  correct  self-induction  for 
use  with  a  Wehnelt,  at  least  over  a  wide  range  of  fre- 
quencies of  interruption.  If  inverse  is  prominent,  try 
a  greater  amount  of  platinum  exposed,  thereby  lowering 
the  frequency  of  interruption. 

5.  Do  not  run  too  hot,  and  if.  possible  enclose  inter- 
rupter in  a  sound-proof  box,  or  place  outside. 


Fig.  48.    **Eotax"  interrupter. 

6.  Be  sure  that  connections  are  made  to  the  proper 
terminals. 

7.  Do  not  try  to  operate  on  alternating  current  with- 
out a  rectifier.  This  has  been  done  in  a  few  instances, 
but  is  not  advised. 

The  Mercury  Interrupter. — Various  forms  of  inter- 
rupters using  mercury  have  been  invented,  and  have  some 
advantages  for  use  with  heavy  coils.  They  allow  varia- 
tion in  two  essential  particulars,  viz.,  number  of  inter- 
ruptions per  second  and  relative  duration  of  make  and 
break.     Two  forms  are  in  common  use.     In  the  jet  type, 


X-RAY  PHYSICS  101 

Fig.  47,  a  centrifugal  pump  throws  small  streams  of  mer- 
cury against  V-shaped  iron  terminals.  The  motor  speed 
determines  the  number  of  interruptions,  and  raising  or 
lowering  the  iron  decreases  or  increases  time  of  flow  rela- 
tive to  that  of  no  current. 

In  the  Rotax  interrupter,  Fig.  48,  the  mercury  is  thrown 
into  a  ring  revolving  with  the  case.  An  insulating  disc 
with  a  small  conducting  sector  is  mounted  so  that  it  may 
be  moved  to  and  from  the  circumference.  When  in  con- 
tact with  the  mercury,  the  disc  rotates  at  a  speed  depending 
on  the  mercury  speed  and  the  amount  of  immersion  of 
the  disc.  The  latter  is  insulated  from  the  case  and  is 
connected  to  an  external  binding  post.  The  relative  time 
of  current  "on"  and  "off"  varies  with  the  immersion  of 
the  disc  in  the  mercury.  A  small  amount  of  paraffin  oil 
is  used,  forming  a  ring  inside  the  mercury  to  prevent 
oxidation.  A  better  plan,  when  the  apparatus  will  per- 
mit, is  to  use  illuminating  gas  in  the  case,  which  reduces 
contamination  of  the  mercury  and  enables  long  periods  of 
operation  without  refilling.  If  gas  is  used,  a  small  burner 
should  be  connected  to  the  cavity  and  kept  burning,  and 
the  current  should  never  be  turned  on  until  this  light 
continues  to  burn,  as  severe  explosions  may  result  by  spark 
ignition  of  an  air-gas  mixture.  Recent  forms  have  a 
safety  valve  to  protect  against  explosion. 

A  suitable  capacity  must  always  he  connected  to  the 
terminals  of  interrupters  of  this  type.  The  amount  of 
this  capacity  will  vary  with  different  inductances  of  the 
primary  and  to  some  extent  with  the  frequency  of  the 
interruption. 

Operating  Notes. — Carefully  read  and  preserve  any  di- 
rections furnished  by  the  maker  of  the  interrupter  used. 
If  none  are  at  hand,  and  trouble  arises,  some  one  or  more 
of  the  following  may  be  found  to  account  for  it. 


102  U.  S.  ARMY  X-RAY  MANUAL 

1.  No  current  in  any  position  of  the  disc.  Look  for 
poor  contacts,  either  from  bad  brush  on  revolving  case, 
loose  binding  posts,  or  broken  wires.  The  mercury  should 
be  examined  to  be  sure  that  there  is  enough  and  that  the 
oxide  does  not  prevent  contact. 

2.  Very  heavy  primary  current  and  little  or  no  second- 
ary current  or  voltage.  Examine  capacity  to  see  if  it  is 
punctured ;  if  so,  renew  at  once.  If  condenser  is  all  right, 
see  if  disc  is  free  to  turn  and  is  not  immersed  too  far 
by  reason  of  an  overcharge  of  mercury. 

3.  Be  sure  to  keep  the  required  amount  of  oil  in  the 
case,  as,  if  there  is  too  little  it  becomes  carbonized  by  the 
arc  and  gives  trouble. 

4.  The  mercury  must  be  kept  clean.  When  it  is  dirty, 
oxidized,  or  emulsified  with  oil,  either  clean  by  filtering 
and  washing  or  put  in  new  mercury. 

A  coil  in  which  a  current  is  changing  always  develops 
an  active  opposition  to  the  alternation  of  current.  On  an 
attempt  to  increase  the  current,  the  coil  acts  as  an  op- 
posing generator,  and  when  current  falls  the  generator 
action  reverses.  This  action  is  due  to  self-induction.  The 
opposing  voltage,  when  we  change  current  at  the  rate  of  1 
ampere  per  second,  is  an  important  factor  in  behavior  of 
the  coil,  and  is  named  the  coefficient  of  self-induction. 

On  account  of  self-induction,  no  really  instantaneous 
change  of  current  can  take  place,  arid  the  response  to 
variable  voltage  will  depend  on  this  feature  of  the  coil 
and  on  the  rate  at  which  we  attempt  to  make  current 
changes.  Each  coil  is  an  individual  in  this  respect,  and 
one  should  find  by  trial  the  conditions  under  which  it  op- 
erates best  for  each  purpose,  and  then  adhere  to  these 
conditions.  A  little  time  spent  in  this  way  will  save 
much  time  and  annoyance  later. 

Tubes  for  Use  with  Coils. — The    current   wave    from    a 


X-RAY  PHYSICS 


103 


coil  is  quite  different  from  that  from  a  transformer.     The 
current  consists  of  a  series  of  short  rushes  with  considerable 


Fig.  49.     Oscillogram — induction   coil  current  with   a  gas  mercury- 
interrupter. 


Fig.  50.     Oscillograms — induction   coil   currents   with   Wehnelt   in- 
terrupter. 

time  between  each  impulse.  Fig.  49  shows  the  variations 
of  current  with  time  on  an  induction  coil  with  a  good 
mercury  interrupter.     Fig.   50,  two   curves  with  a  AYeh- 


104  U.  S.  ARMY  X-RAY  MANUAL 

nelt  break.  Note  the  large  amount  of  inverse  in  the  latter. 
In  order  that  the  tube  current  may  not  lower  the  voltage 
below  the  required  point,  it  is  essential  to  have  gas  tubes 
at  relatively  high  vacuum,  or  hard.  Thus  we  must  have 
small  tube  currents. 

Readings. — Milliampere  and  spark  gap  readings  are  far 
less  reliable  guides  for  radiography  when  using  coils  than 
on  transformers.  The  gap  shows  peak  voltage  which  maj^ 
bfe  high  but  transient.  As  the  ordinary  milliammeter  indi- 
cates the  difference  between  direct  and  inverse,  one  may  get 
0  reading  and  yet  have  the  tube  operating. 

Portable  Coils. — Portable  coil  outfits  are  so  varied  as  to 
make  brief  description  impossible.  Those  heretofore  in  use 
were  largely  of  the  ''Tesla"  type. 

The  electric  lighting  current  is  stepped  up  to  about 
2000  volts  by  a  small  step-up  transformer,  if  the  supply 
is  from  an  alternating  current  line. 

If  the  current  is  direct,  the  circuit  is  made  and  broken 
by  some  form  of  vibrating  interrupter,  giving  much  the 
same  effect  in  the  transformer  as  though  an  alternating 
current  was  used. 

The  2000  volt  current  from  the  secondary  of  the  step-up 
transformer  charges  a  condenser.  The  condenser  is  dis- 
charged through  a  few  turns  of  wire  wound  around  the 
outside  of  a  secondary,  consisting  of  a  large  number  of 
turns  of  fine  wire.  The  discharge  of  the  condenser  is 
at  an  enormous  frequency,  and  high  voltages  of  high  fre- 
quency are  generated  by  the  Tesla  coil. 

As  the  current  delivered  by  the  Tesla  coil  is  alternat- 
ing, a  different  form  of  tube  must  be  used  from  that  for 
other  types  of  x-ray  generator,  if  best  results  are  de- 
sired. This  special  tube  has  a  valve  arrangement  built 
into  it  which  tends  to  suppress  one  wave  of  the  current. 

Fast  Work. — From  what  has  gone  before,  it  is  clear  that 


X-RAY  PHYSICS  105 

the  same  radiographic  density  can  be  secured  in  a 
great  variety  of  exposure  times.  Certainly,  for  the  in- 
experienced operator  high  speed  is  inadvisable.  If  3  to 
10  seconds  would  give  the  most  desirable  exposure,  an 
error  of  one  second  would  give  a  fairly  good  plate.  On 
power  such  that  i/>  second  is  best,  an  error  of  one  second 
in  judgment  or  execution  would  exceed  the  latitude  of  the 
plate. 

The  conditions  for  fast  work  are : 

1.  Small  target-plate  distance. 

2.  Very  large  current. 

3.  High  voltage. 

4.  Fast  plates  or  intensifying  screens. 

The  disadvantage  of  the  first  is  distortion  and  haze 
of  outline,  due  to  size  of  electron  focus;  of  the  second 
danger  of  melting  the  target,  and  difficulty  in  setting 
to  proper  voltage.  AYhen  high  voltage  is  used,  the  even- 
ing up  of  penetration,  as  well  as  the  increase  of  scattering 
with  high  penetration  rays,  tends  to  give  flat  plates.  Very 
fast  plates  and  ordinary  plates  with  screens  allow  little 
latitude  of  exposure.  Screens  also  may  register  their  own 
dust  or  surface  defects. 

Photographic  Density  and  Character  of  Negative. — 
Considerable  objection  has  been  made  to  the  use  of  photo- 
graphic plates,  films,  or  paper  in  the  study  of  this  type 
of  radiation.  Much  of  the  adverse  criticism  is  well  founded, 
for  the  following  reasons :  The  unaided  eye  is  a  poor 
judge  of  comparative  absorption  of  light  by  a  negative; 
only  by  means  of  comparison  involving  photometric  appara- 
tus can  one  be  fairly  sure  of  correct  measurement.  If  an 
unexposed  or  clear  portion  of  a  negative  transmits  an  arbi- 
trary amount  of  light,  Q,  an  area  transmitting  50  per  cent 
or  half  as  much  w^ould  be  said  to  have  an  opacity  of  2 ; 
and  the  logarithm  of  this  opacity  would  be  named  the 


106 


U.  S.  ARMY  X-RAY  MANUAL 


density  of  this  portion  of  the  negative.  It  has  been  found 
that  density  determined  in  this  way  is  proportional  to  the 
amount  of  silver  reduced  per  unit  plate  area.  Transmis- 
sions, opacities,  and  densities  are  related  as  follows : 


Transmission  per  cent  Opacity 

0 
100       (Clear  glass)   1 
90  10/9  =  1.11 

80  10/8  =  1.25 

70  10/7  =  1.43 

60  10/6  =  1.66 

50  10/5  =  2.00 

40  10/4  =  2.50 

30  10/3  =  3.33 

20  10/2  =  5.00 


Density 
D 
0  (Log  1 

.104 

.223 

.358 

.507 

.693 

.916 
1.203 
1.609 


0) 


When  the  intensity 
and  quality  of  radiation 
remain  fixed,  the  expo- 
sure varies  only  with 
the  time.  Suppose  that 
Kt  =  E  where  K  de- 
pends on  the  nature  and 
intensity  of  the  radia- 
tion. Plotting  E  and  D, 
there  remains  a  line  ap- 
proximately as  shown  in 
Fig.  51.  A  portion  of 
this  line  AB  is  nearly 
straight;  below  A  and  above  B  it  is  curved  somewhat,  as 
shown.  If  AB  is  produced  to  cut  the  density  axis  at  /,  01 
is  named  the  inertia  of  the  plate.  The  portion  AB  of  the 
plot  is  the  region  of  proper  exposure.     Above  B  the  den- 


/  £ 

Fig.  51.  The  relation  between  ex- 
posure and  density  of  a  photographic 
plate.  Below  A — underexposure.  Be- 
yond B — overexposure.  01 — inertia 
of  the  plate. 


X-RAY  PHYSICS  107 

sity  fails  to  increase  in  proportion  to  exposure  and  is  the 
region  of  over-exposure.  In  fact,  if  the  exposure  is  car- 
ried too  far,  the  density  falls  off  and  a  reversal  may  occur. 

The  slope  of  the  line  AB  or  the  ratio  BM/AM  =  7 
is  named  the  development  factor ;  For  under-develop- 
ment  T  is  small  and  contrast  is  low.  For  longer  de- 
velopment, the  line  swings  counter-clockwise  on  /  as  a 
pivot.  The  point  where  one  should  stop  is  a  matter  to  be 
governed  by  experience.  In  ordinary  photography  7 
ranges  from  .8  to  1.3 ;  probably  no  accurate  determination 
can  be  made  of  the  most  desirable  conditions  until  some 
agreement  is  reached  as  to  the  best  quality  of  negative  for 
specific  purposes. 

The  inertia  of  the  plate  is  not  affected  by  time  of  de- 
velopment. A  fast  plate  is  one  where  01  is  small.  A  plate 
of  great  latitude  is  one  where  exposure  difference  for  A  and 
B  is  large.  The  speed  of  a  plate  is  determined  by  the 
inertia  01  and  is  expressed  in  arbitrary  sensitometer  units. 

The  conditions  during  development  fix,  for  a  given  plate, 
a  time  beyond  which  development  should  not  be  carried 
on  account  of  fog.  In  x-ray  work,  the  use  of  high  pene- 
tration  on  thick  patients  tends  to  fog  by  cross  scatter^ 
radiation,  and  this  may  be  noticed  long  before  developer 
fog  becomes  troublesome. 

As  a  means  of  measurement,  we  may  utilize  different 
portions  of  the  same  plate  under  different  physical  condi- 
tions to  learn  whether  the  radiation  effects  on  the  various 
portions  are  or  are  not  alike.  For  example,  if  a  canstant 
voltage  is  used  at  constant  distance,  the  exposure  varies 
as  the  product  of  current  and  time — so  that  20  ma.  for 
2  seconds  and  40  ma.  for  1  second  should  give  equal 
density  with  equal  development,  provided  the  rise  and 
fall  of  voltage  be  alike  in  the  two  cases. 


108  U.  S.  ARMY  X-RAY  MANUAL 

Certain  terms  are  in  common  use  when  negatives  are 
described,  and  should  be  understood. 

Contrast  refers  to  the  amount  of  difference  in  darken- 
ing for  a  small  difference  of  exposure.  Thus,  if  rays  pass 
through  bone  and  flesh,  there  is  a  variation  in  the  amount 
of  radiation  reaching  the  plate,  due  to  difference  of  absorp- 
tion; when  this  results  in  a  marked  difference  in  darken- 
ing, the  negative  is  ' '  contrasty. "  Contrast  depends  on  the 
nature  of  the  plate  and  the  development,  and  to  a  great 
extent  on  the  quality  of  the  radiation  used.  If  the  beam 
is  too  penetrating,  contrast  is  reduced,  for  if  rays  pass 
through  bone  and  flesh  equally  well,  there  would  be  no 
contrast.  Too  ''soft"  radiation  will  fail  to  get  through 
the  denser  portion  and  will  give  high  contrast  but  poor 
detail  in  thick  parts.  The  amount  of  contrast  to  be  de- 
sired will  vary  with  the  work  to  be  done.  A  plate  showing 
fine  bone  detail  and  contrast  may  show  but  little  of  the 
soft  tissue. 

Detail  refers  to  the  fineness  of  the  marking  of  light  and 
shade.  Thus,  a  mastoid  plate  should  show  minute  struc- 
ture, or  lines  of  light  and  shade  should  show  sharp  grada- 
tion or  density  change.     Detail  depends  on: 

1.  Breadth  of  tube  focal  spot. 

2.  Distance  of  target  from  plate. 

3.  Distance  of  part  to  be  radiographed  from  plate. 

4.  Complete  immobilization  of  patient. 

5.  Correct  exposure  and  development. 

Exposure  Table. — Many  attempts  have  been  made  to 
work  out  exposure  tables  such  that  inexperienced  operators 
can  get  favorable  results.  Without  doubt  the  best  work 
is  done  when  spark  gap,  current,  and  time  are  chosen 
with  reference  to  the  individual  case  in  hand,  and  any 
operator  who  cannot  improve  on  the  results  secured  by 
adhering  to  any  single  table  is  unfit  for  the  work. 


X-RAY  PHYSICS 


109 


As  a  general  guide  in  starting  work,  a  uniform  rather 
high  gap  may  be  used — say  5  inches,  and  a  uniform  tar- 
get-plate distance — say  20  inches,  except  for  chest,  where 
28  inches  is  advised.  With  all  this  understood,  the  average 
of  reports  from  many  sources  gives  the  following  table 
for  a  patient  of  about  150  pounds  weight  and  a  Seed 
x-ray  plate.  Some  people  prefer  a  shorter  gap  for  most 
work  [p-a  head  work  excepted],  and  certainly  with  the 
ordinary  solid  tungsten  target,  medium  focus  Coolidge 
tube,  better  negatives  result  from  proper  exposure  on  a 
four-inch  gap  than  on  a  five-inch  one ;  this  wall  require 
about  50  per  cent  increase  in  time  of  exposure  for  the 
same  distance  and  current. 


Part                     Time :  sec. 

Head,  A-P 

12 

Head,  Lat. 

6 

Neck 

3 

Shoulder 

31/2 

Elbow 

11/2 

All  exposures  on  5"  gap. 

Wrist 

1 

40  ma.  20"  distance  ex- 

Kidney 

3     5 

cept  chest,  which  is  at 

Bladder 

3     5 

28". 

Hip  joint 

5     7 

Pelvis 

5    7 

Knee 

2 

Ankle 

11/2 

Lumbar  spine 

5—6 

Teeth   (slow  film) 

4 

Teeth   (fast  film) 

11/2 

Chest    (at  28") 

21/9—4 

Notes:  (a)  For  parts  above  average  thickness,  increase 
time  considerably  more  than  in  proportion  to 
increase  of  thickness. 


110  U.  S.  ARMY  X-RAY  MANUAL 

(b)  If  it  is  necessary  to  work  at  other  distances 
than  20",  use  the  following  table  of  multiply- 
ing factors: 

Distance  Time  factor  Distance  Time  factor 

15"                       .6  21"                       1.1 

16  .6  22                     '   1.2 

17  .7  23                         1.3 

18  .8  24                        1.4 

19  .9  25                         1.6 

20  1.0 

For  ''Diagnostic  plates,"  reduce  time  by  14.  For  doii.- 
hie  coated  Eastman  films  use  half  the  time. 

With  intensifying  screens  no  fixed  rule  can  be  given.  A 
reduction  factor  may  be  found  for  the  screen  used  as 
indicated  on  pages  112-114. 

Plates  and  Films. — Photographic  plates  and  films  con- 
sist of  a  thin  layer  of  gelatin  containing  a  salt  of  silver 
and  spread  on  glass  or  celluloid.  Light  and  x-rays  cause 
a  change  in  the  silver  salt  such  that  suitable  chemicals, 
called  developers,  act  on  the  portions  that  have  received 
the  radiation,  changing  the  silver  compound  to  metallic 
silver,  and  thus  rendering  those  portions  more  or  less 
opaque  to  light.  The  opacity  produced  will  depend  on  the 
amount  of  radiant  action,  on  the  sensitiveness  of  the  emul- 
sion, and  on  the  development.  Those  portions  receiving 
much  light  or  x-rays,  when  fully  developed,  may  be  quite 
opaque ;  other  portions  may  be  entirely  or  nearly  trans- 
parent. 

After  development  the  plate  is  washed  and  placed  in  a 
''fixing"  bath  which  removes  the  unused  silver  salt,  as 
shown  by  the  disappearance  of  the  cream  color  of  the  emul- 
sion, rendering  the  parts  not  radiated  and  developed  trans- 
parent. 


X-RAY  PHYSICS  111 

All  plates  sensitive  to  x-rays  are  also  sensitive  to  ordi- 
nary light  and  hence  they  must  be  entirely  protected  from 
ordinary  white  light  until  finished. 

The  emulsion  is  an  example  of  unstable  chemical  struc- 
ture and  may  be  injured  by  (1)  moisture,  (2)  high  tem- 
perature, (3)  contact  with  other  material,  (4)  exposure 
to  light  or  x-rays,  (5)  bending.  Plates  should  be  kept  in 
the  original  boxes,  on  edge,  in  a  cool  dry  room,  well  pro- 
tected from  x-rays.  No  more  plates  should  be  put  up  in 
envelopes  than  are  likely  to  be  used  in  the  next  two  or 
three  days. 

Filling  Envelopes  and  Cassettes. — X-ray  plates  are  used 
either  in  envelopes  or  in  plate-holders,  called  cassettes. 
It  is  quite  essential  that  in  regular  work  the  emulsion  side 
should  be  toward  the  patient.  To  insure  this  when  using 
envelopes,  arrange  the  envelopes  to  be  filled  before  darken- 
ing the  room.  Put  black  and  yellow  envelopes  in  alterna- 
tion with  the  end  flaps  down,  insert  plate  with  emulsion  side 
down,  i.  e.,  so  that  the  flap  will  fold  over  the  hack  of  the 
plate ;  then  insert  the  flap  end  first  in  the  yellow  envelope 
with  the  emulsion  down,  so  that  the  flap  of  the  outer  en- 
velope also  folds  over  the  back.  Then  place  the  smooth 
side  of  the  envelope  toward  the  target.  A  soft  brush 
is  useful  to  remove  dust  from  plates  and  cassettes. 

In  using  cassettes  without  screens,  put  the  emulsion  side 
down.  This  side  can  be  determined  by  sighting  across  the 
surface,  as  it  appears  dull  as  compared  with  the  glass  side, 
or  touching  the  tongue  to  the  extreme  corner  of  the  plate — 
the  emulsion  side  will  be  slightly  sticky.  Form  the  habit 
of  closing  partl}^  empty  plate  boxes  at  once  after  filling 
envelopes  or  cassettes. 

Attention  is  called  here  to  the  new  double-coated  film 
which  is  used  to  considerable  extent.  In  this  case  there 
is  no  difference  in  the  two  sides  of  the  film  and  no  at- 


112  U.  S.  ARMY  X-RAY  MANUAL 

tention  need  be  paid  in  placing  it  in  the  special  holders 
provided.  It  should  be  borne  in  mind,  however,  that  these 
films  must  be  handled  with  great  care.  Finger  prints  are 
much  more  likely  to  show  and  both  sides  of  the  emulsion 
must  be  protected  from  moisture  and  scratches.  Great 
care  must  also  be  taken  not  to  wrinkle,  bend  or  twist 
these  films  before  exposure.  For  this  reason  it  is  undesir- 
able to  attempt  to  use  them  in  the  ordinary  black  or  yellow 
envelopes  usually  supplied.  They  should  be  used  in  cas- 
settes or  in  the  special  holder  furnished  for  the  purpose. 

Intensifying  Screens. — When  u^ing  intensifying  screens 
the  usual  practice  in  thisj30untry  isto  allow  the  rays  to 
'pas&^Jhraiigh  tlie_  glass_to  the^^mulsion  and  then  to  the 
screen  surface.  Consequently  the^  negative,  when^  viewed 
wi^  the  einulsion  side  toward^jthe^eye,  i^^j^versed  3s_jto 
right  and  Jeft  as  compared  with^the  usual  _glate;^_The 
screen  sjiould  be  firmly  fixed  to  the^^^^k_of_Jhe_casset^e 
and   should    be   kei)t  jcrupiilouslyi   clean;    wipe   off   dust 

^rth  a  dean  cloth,  and  never  touch  the  surfacejwiili^wet_or_ 
greasy  fingers.    I ns^  cleaned  plate  with  emulsion  side  up, 
^^be  sure  that  the  springs  press  the  screen  firmly  against 
the  plate.    On  account  of  the  varj^able_x-ray^pacity  of  the 
glass  at  present  in  use,  screen  work  witli  plates  is  rather 

^uncertain.    Be  sure  to  keep  screen  clean  by  not  letting  it 
g^et^^t,  dirt^  or  dusty. 

It  is  quite  inipossible  tojie  sure  of  the  speed  of  the  vari- 
ous ^ere^s^  in  actual  use,  inasmuch  as  this  depends  on 
so  many  conditions,  ^such  as  amountoJ  use,  and  the  general 
care  which  has  been  exercised  in  handling,  as  welTas  their 
initial  speed.  "      *     • 

In  order  that  the  proper  exposure  may  be  given  it  is  well 
to  determine  the_multiplying  factor  by  which  the  screen 
increases  the  normal  speed   of  the   plate.     This  may  b'e" 

^ea^lyjdone  by  the  use  of  a  film  of  proper  size  in  the  screen 


X-RAY  PHYSICS  113 

holder,  exposed  at  the  same  time  with  one  in  an  ordinary 
em^elope  or  container  laid  ontop_ofthe  screen7"~"Tliis  en- 
velope shonld  be  cross^rnrgTwith  lines  approximately  I/2 
iii£li_  apart,  and  a  heavy  sheet  of  lead  placed  to  cover  a_ll 
except  oi'ie  end  division,  beino;:  snre  that  iirmjccnpies  thi^ 
division.  Make  a  vei'y  brief  exposure  at  low  power  and 
considerable  distance,  usin^^a_Jimer,  if  one  is  available, 
and  leaving  the  tube,  machine,  tim^i^^and  distance  un- 
changed; slide  the_  sheet  of  lead  back,  leaving  two  divi- 
sions exposed;  and  j:£i)eat  the  exposure.  Do  this  for  all 
of  the  film  and  develop  both  films  at  the  same  time  and 
in  the  same  developer."""^* 

It  will  be  evident  that  if  there  were  15  divisions,  the 
one  which  was  exposed  first  received  15  exposures,  the 
next  14,  etc.  The  last  may  be  numbered  1,  the  next  2, 
etc.  If  it  should  be  found  that  the  film  in  the  envelope, 
and  not  affected  by  the  intensifying  screen,  required  12 
of  these  exposures  to  give  the  same  blackening  as  number 
one,  with  the  intensifjang  screen,  it  is  clear  that  1/12  of 
the  time  required  with  no  screen  should  be  used.  This 
procedure  is  somewhat  more  reliable  if  exposures  can  be 
through  a  rectangular  block  of  paraffin,  as  the  speed  of 
some  screens  seems  to  vary  considerably  according  to  the 
filtration  which  the  rays  have  received  before  reaching  the 
emulsion.  Fig.  52  shows  such  a  pair  of  films  for  a  particu- 
lar screen.  After  the  determination  of  the  speed,  it  should 
be  marked  on  the  cassette  so  as  to  be  available  during 
use. 

Care  in  Handling  Plates  and  Films. — In  all  cases,  plates 
and  films  must  be  kept  well  protected  by  lead  when  in  the 
x-ray  room.  A  good  lead-lined  box  on  casters  is  very  use- 
ful for  this  purpose,  and  where  much  work  is  done,  one  for 
exposed  and  another  for  unexposed  plates  should  be  pro- 


114 


U.  S.  ARMY  X-RAY  MANUAL 


vided,  or  a  partition  plainly  marked  ''EXPOSED"  and 
''UNEXPOSED,"  dividing  a  single  box  may  be  used. 


Fig.  52.     Gradation   due   to   successive   equal   exposures   with    and 
without  intensifying  screen,  a,  without  screen,  &,  with  screen. 

The  following  cautions  may  be  given  to  those  unfamiliar 
with  darkroom  work: 

1.     Never  handle  plates  or  films  with  wet  or  greasy  fin- 


X-RAY  PHYSICS  115 

gers,  either  before  or  after  exposure.     ]\Iarks  and  streaks 
are  sure  to  result,  even  if  the  emulsion  is  not  destroyed. 

2.  Learn  to  handle  plates  without  touching  the  emulsion 
side,  even  with  dry  lingers. 

3.  Mix  all  solutions  according  to  instructions  and  see 
that  chemicals  are  actually  dissolved. 

4.  Keep  all  trays  clean,  and  do  not  use  insufficient  or 
too  old  developer;  stains  are  hard  to  remove,  and  the  cost 
in  time  and  money  is  excessive  if  it  is  attempted. 

5.  In  tray  development,  be  sure  that  the  developer  cov- 
ers the  entire  plate  at  once.  Tilt  the  tray  slightly  on  insert- 
ing the  plate,  and  tilt  the  tray  in  several  directions  to 
ensure  complete  wetting  of  the  film  as  soon  as  possible. 
Keep  tray  in  motion  during  development. 

6.  Do  not  examine  the  plate  by  removing  it  from  the 
developer  until  the  minimum  time  for  full  development  on 
normal  exjDosure  has  elapsed. 

7.  Do  not  try  to  develop  several  plates  in  a  tray  at  one 
time  if  they  overlap. 

8.  Wash  negatives  well  on  removing  from  the  developer, 
before  placing  in  the  fixing  bath. 

9.  Leave  negatives  in  the  fixer  for  some  minutes  after 
they  seejii  to  be  fully  cleared ;  then  wash  thoroughly,  in 
running  water  if  possible. 

10.  Do  not  use  the  same  trays  for  hypo  and  for  devel- 
opment. Mark  hypo  trays  and  keep  them  well  away  from 
developer.    A  little  hypo  in  the  developer  is  fatal. 

11.  Keep  negatives  in  a  dust-free  atmosphere  and  in 
one  location  and  position  until  dry. 

12.  When  the  developer  is  not  in  use,  keep  in  tightly 
closed  containers.  Glass  fruit  jars  with  rubbers  are  as 
good  as  anything  for  small  amounts.  L^se  a  close-fitting 
float  in  tank. 

13.  Don't  try  all  the  developing  formula  you  can  find ; 


116  U.  S.  ARMY  X-RAY  MANUAL 

take  one  advised  for  the  plate  you  use,  and  learn  to  use  it. 

14.  Don't  fix  in  plain  hypo  in  warm  weather.  PJates 
will  frill  if  you  do. 

Tank  Development. — In  tank  development,  the  plate  is 
placed,  while  dry,  in  a  special  frame  or  holder  and 
hung  vertically  in  the  tank  containing  the  developer.  This 
method  is  desirable  when  much  work  is  done.  With  strong 
developer,  stirring  by  moving  the  holders  will  prevent 
vertical  streaks. 

Temperature. — The  action  of  the  developer  varies 
greatly  with  changes  iii  temperature.  Between  60°  F. 
(16°  C.)  and  70°  F.  (22°  C.)  is  best.  Hot  developer  works 
fast  and  is  likely  to  fog  the  plate.  Cold  developer  is  slow 
and  may  not  give  anything  on  a  normal  exposure.  Do  not 
cool  developer  by  adding  ice  or  ice  water,  as  this  dilutes 
the  solution.  When  using  tanks,  cold  or  ice  water  may 
flow  or  stand  around  the  developer  tank  until  a  proper 
temperature  is  reached,  or  put  ice  in  a  fruit  jar  and 
immerse  jar  in  developer. 

Concentration. — If  more  water  is  added  to  a  normal 
developer,  slower  action  will  result.  This  is  sometimes  ad- 
vised in  tank  development,  and  with  screen  plates,  but 
is  not  necessary  if  the  developer  is  stirred  occasionally. 

Plate  Defects. — Plates  are  sometimes  defective,  due  to 
faults  or  accidents  in  manufacture,  but  in  most  cases  of 
complaint  the  trouble  is  due  to  improper  treatment  after 
leaving  the  factory.  If  one  is  sure  of  proper  exposure, 
development,  fixation  and  washing,  and  still  finds  streaks, 
spots,  bubbles,  or  bad  color,  the  plates  may  be  blamed. 
Much  trouble  is  traced  to  the  materials  used  at  present, 
and  in  all  cases  of  doubt  cheek  plates  should  be  made. 
Defects  are  not  likely  to  appear  on  the  same  region  in 
both  negatives.  Looking  across  the  negative  at  any  un- 
evenly illuminated  surface  will  often  show  whether  a  spot 


X-RAY  PHYSICS  117 

is  due  to  a  defect  in  the  glass  or  to  something  on  the  emul- 
sion surface. 

Examining  Negatives. — When  it  can  be  avoided,  plates 
ought  not  to  be  examined  until  dry.  If  they  must  be 
used  while  wet,  care  is  needed  to  avoid  heating  the  gela- 
tin or  it  will  melt  and  completely  ruin  the  negative.  A 
well-diffused  illumination  is  very  desirable ;  it  should  be 
well  under  control  so  as  to  give  a  strong  light  for  dark  nega- 
tives and  a  much  weaker  one  for  thin  ones.  Ground  or  opa- 
lescent glass  is  not  needed  if  a  dull  white  surface  is  illumi- 
nated and  the  plates  are  viewed  by  light  reflected  from  it. 
Fig.  53  shows  a  useful  type  of  illuminator. 

Developer  Action. — The  action  of  developer  on^an  ex- 
posed plate  is  rather  a  complicated  matter.  For  the  pres- 
ent  purpose  we  may  omit  discussion  further  than  to  say  ^ 
that  with  any_a^ctive  developing  agent  a  suitable  amount 
of  alkali  Js  indispensable.  Do  not  vary  the  proportion 
shown^in  reliable^and  tested  formula,  at  least  in  routine 
work.  Development  at  any  given  depth  below  the  surface 
of  the  emulsion  can  only  take  place  W'hen  the  active  de- 


veloping solution  has  reached  that  point  in  sufficient 
amount  to  cause  the  chan^e_required.  Hence,  dilute  or 
partly  exhausted  developer  requires  more  time.  Prolonged 
action  of  develo;Qer  on  the  emulsion  will  cause  a  darkening 
even  with  little  or  no  exposure,  and  to^strong  developer 
wilFover-develop  the  outerlayers  before  the  deeper  ones, 
are  affected.  Plates  exposed  to  x-rays  are  developable, 
through  the  entire  depth  of  emulsion,  while  light  only  af- 
fects_the  outer  layer.  Hence,  if  fog  can  be  avoided,  x-ray 
plates^  will  increase  in  density"  with  longer  development  to 
a  greater  extent  than  will  negatives  exposed  to  light  The 
action  of  ^tassium  bromide  restrains  or  delays  develop- 
ment at  the  surface  an'5^  ten^s  To  keep  the  ' '  whites ' '  clear. 
All  developers  are  absorbers  of  oxygen  and  are  useless  when" 


118 


U.  S.  AR^IY  X-RAY  MANUAL 


X-RAY  PHYSICS  119 

they  no  longer  absorb  this  gas.  For  this  reason,  they  ought 
to  be  protected  from  air  when  not  in  use. 

"Hypo"  or  Fixing. — The  purpose  of  fixation  is  the  re- 
moval of  all  unreduced  silver,  leaving  the  small  specks  of 
metallic  silver  suspended  in  the  gelatin  film.  Any  unre- 
duced silver  left  in  the  gelatin  will  sooner  or  later  discolor 
and  ruin  the  negative.  By  using  acid  and  alum,  the  clear- 
ing is  improved  and  the  film  of  gelatin  hardened.  "Hypo" 
must  be  thoroughly  removed  by  washing  half  an  hour  to 
one  hour  in  running  water,  so  that  hypo  crystals  will  not 
form  in  the  gelatin,  ruining  the  negative.  If  the  bath 
is  too  acid  a  rash  wall  appear  on  the  surface  of  the  gela- 
tin. The  acid  should  be  partly  neutralized  by  the  addition 
of  sodium  carbonate.  If  the  bath  appears  milky,  it  gener- 
ally lacks  acid  and  can  be  cleared  by  the  addition  of  acetic 
acid. 

Fog. — It  is  extremely  important  for  every  roentgenol- 
ogist to  realize  the  full  effect  of  fog  produced  on  the  nega- 
tive in  development.  This  fog  is  the  result  of  chemical 
action  and  is  alw^ays  produced  to  a  certain  extent.  It  is 
not  uniformly  distributed  over  the  plate  in  any  case,  and 
is  related  to  a  certain  extent  to  the  exposure  at  the  points 
where  it  shows.  It  has,  always,  the  effect  of  blotting  out 
the  finer  details.  In  a  properly  exposed  and  developed 
plate  these  finer  details  show  as  light  areas  against  a  slight- 
ly darkened  background,  as,  for  example,  in  the  case  of  a 
mastoid  plate. 

As  soon  as  fog  is  produced  to  such  an  extent  that  these 
clear  white  lines  become  smoky,  contrast  W'ith  the  slightly 
darker  background  and  adjacent  areas  may  be  entirely  lost. 
Fog  will  always  be  produced  if  the  developer  is  too  w^arm, 
if  improperly  mixed,  or  if  the  time  of  development  is  too 
long.  The  only  way  to  avoid  it  for  a  given  plate  is  to 
use  a  proper  concentration  of  the  developer,  a  proper  tern- 


120  U.  S.  ARJ\1Y  X-RAY  MANUAL 

perature,  and  such  an  exposure  as  will  enable  complete 
development  to  be  made  before  fogging  action  becomes  ef- 
fective. 

The  roentgenologist  should  invariably  remember  that  a 
proper  distribution  of  shadows  on  his  plate  or  fluoroscopic 
screen  furnishes  the  only  physical  basis  for  diagnostic  use 
of  his  radiation,  and  to  avoid  the  necessity  of  passing  upon 
indefinite  and  unsatisfactory  plates  it  is  just  as  essential  to 
pay  attention  to  the  darkroom  conditions  as  it  is  to  consider 
proper  position  and  exposure.  The  diagnoses  made  on  the 
basis  of  shadows  that  are  so  faint  as  to  be  invisible  to  the 
majority  of  observers  introduce  a  very  considerable  ele- 
ment of  imagination,  and  are  relatively  unsafe  even  for 
those  who  claim  successful  results  on  such  a  basis. 

Developing  Formiilae. — Most  x-ray  operators  had  been 
using  a  hydrochinon-metol  developer  prior  to  the  shortage 
of  metol.  Certain  substitutes  for  metol  have  been  marketed 
of  more  or  less  value.  The  following  formulae  have  been 
found  fairly  good  in  practice : 

Hydrochinone — 

Water  (warm)    1       gal.         5       gal. 

Sodium  sulphite  (dry)    .  .   8       oz.         40       oz. 

Hydrochinone  II/2    "  IY2  " 

Sodium  carbonate  (dry)      8        "  -iO       '' 

Pot.  bromide 1       dr.  5       dr. 

Mix  in  order  named. 

Good  for  tank  development.. 

Elon-Hydrochinone — 

(Dissolve  these  chemicals  in  order  named:) 

Water 20  oz. 

Elon    20  grs. 

Sulphite  of  soda  (dry) 1  oz. 

Hydrochinone 80  grs. 


X-RAY  PHYSICS      •  121 

Carbonate  of  soda  (dr^O 1  oz. 

Potassium  bromide 8  grs. 

Good  for  tank  development. 

Edinol-Hydrochinone — 

Solution  A 

Boiling  distilled  water 32  oz. 

Sodium  sulphite  (dry)   6  oz. 

Edinol    5  dr. 

Hydrochinone    1  oz. 

Potassium  bromide 6  dr. 

Solution  B 

Water 32  oz. 

Potassium  carbonate  2  oz. 

Use  one  ounce  of  Solution  A,  one  ounce  of  Solution  B 
and  two  ounces  of  water.    Develop  6  to  9  minutes. 

Good  for  tray  development. 

Metabisulphite-Hydrochinone. — ^A  professional  photog- 
rapher doing  considerable  x-ray  development  recommends 
the  following  developer  as  very  satisfactory  for  general 
work : 

Mix  in  order  named. 

Solution  A 

Water   200  oz. 

Hydrochinone    4  oz. 

Potassium  metabisulphite    10  gr. 

Potassium  bromide    50  grs. 

Solution  B 

Water  200       oz. 

Sodium  sulphite I14  lbs. 

Caustic  soda 214  oz. 

These  solutions  keep  well  in  stock.  For  use,  mix  in 
equal  parts. 


1^2  U.  S.  ARMY  X-RAY  MANUAL 

Fixing"  Bath  Formulae. — An  acid  hypo  fixing  bath  may 
be  prepared  as  follows: 

Water  64  oz. 

Hypo 16  oz. 

When  fully  dissolved  add  the  following  hardening  solu- 
tion: 

Water 5  oz. 

Sulphite  of  soda 1  oz. 

Acetic  acid  (28%  pure) 3  oz. 

Powdered  alum 1  oz. 

If  preferred,  1  ounce  of  citric  acid  may  be  substituted 
for  acetic. 

This  bath  may  be  made  up  at  any  time  in  advance  and 
may  be  used  so  long  as  it  retains  its  strength,  or  is  not 
sufficiently  discolored  hy  developer  carried  into  it  to  stain 
the  negatives. 

Chrome  Alum  Fixing  Bath. — This  bath  has  good  keep- 
ing qualities,  fixes  clean  and  remains  clear  after  long  con- 
tinued use. 

A 

Pure  water 96  oz. 

Hypo    2  lbs. 

Sulphite  of  soda 2  oz. 

B 

Pure  water 32  oz. 

Chrome  alum 2  oz. 

Sulphuric  acid,  C.  P %  oz. 

Mix  chemicals  in  order  named. 

When  dissolved,  slowly  pour  B  into  A  while  stirring  rap- 
idly. 

Notes  on  Fixing^. — Hypo  is  cheaper  than  spoiled  plates. 
Use  plenty  and  renew  often.  Wash  all  plates  very  thor- 
oughly to  remove  hypo. 


X-RAY  PHYSICS  123 

Do  not  strengthen  an  old  weak  hypo  bath.  Throw  it 
away  and  make  a  new  one.  It  may  fix,  but  it  is  sure  to 
spoil  plates  sooner  or  later. 

Failure  to  wash  off  developer  will  quickly  spoil  a  fixing 
bath. 

Stained  plates  are  usually  due  to  one  or  more  of  the  fol- 
lowing causes: 

Too  warm  developer. 

Too  long  development  of  under-exposed  plates. 

Exhausted  hypo  bath. 

Lack  of  acidity  of  the  hypo  bath. 

Reducing  Dense  Negatives — 

Solution  No.  1 

Water   16  oz. 

Potassium   f erricyanide 1  oz. 

Solution  No.  2 

Water 16  oz. 

Hypo 1  oz. 

Place  plate  in  Solution  No.  2  sufficient  to  cover  it,  then 
add  a  small  quantity  of  No.  1,  and  watch  it  carefully.  If 
it  reduces  too  slow^ly,  add  more  of  No.  1.  If  only  too 
dense  in  places,  apply  the  solution  carefully  with  a  brush 
or  tuft  of  cotton. 

Wash  in  running  water  at  least  a  half  hour  after  re- 
ducing. 

Note. — Make  negative  properly  and  avoid  reduction. 

Darkroom. — The  first  consideration  in  a  darkroom  is  the 
complete  exclusion  of  ordinary  light.  All  windows,  cracks, 
knot  holes,  key  holes,  etc.,  must  be  stopped  by  opaque  ma- 
terial. If  possible,  an  entrance  by  corridor  or  winding 
way  should  be  used.  If  a  door  is  used  it  should  fasten  on 
the  inside,  so  that  no  one  can  open  it  at  an  inopportune 
time. 


124 


U.  S.  ARMY  X-RAY  MANUAL 


The  usual  emulsion  on  x-ray  plates  is  quite  insensitive 
to  red  or  orange-red  light.  A  very  small  intensity  of 
blue  or  white  light  will  ruin  a  plate.  The  quality  of  light, 
not  the  amount,  is  what  must  be  considered,  and  enough 
of  a  safe  light  may  be  used  to  see  clearly  what  one  is 
doing  without  danger  of  fogging  a  plate,  if  the  operator 
is  not  too  slow.  The  inner  walls  of  the  room  should  be 
painted  red  or  orange,  not  black.  A  ruby  20-watt  lamp, 
four  or  five  feet  above  the  working  shelf  with  a  translu- 
cent shade  below  it  covered  with  postoffice  paper,  will 
give  a  diffuse  illumination  of  the  room  very  desirable  for 


Fig.  54.  Simple  arrangement  of  light  for  developing.  The  slide 
contains  a  white  and  a  ruby  glass  with  yellow  (P.O.)  paper  between. 
A  clear  lamp  is  used. 

work.  Test  the  light  by  placing  an  opaque  object  on  a 
small  plate.  Expose  on  the  shelf  for  two  minutes  and 
develop  full  time ;  if  not  fogged,  the  light  is  safe  for  that 
make  of  plate.  If  one  desires  to  time  development  by  look- 
ing through  the  plate,  an  arrangement  as  shown  in  Fig. 
54  or  one  as  sold  by  some  dealers  is  desirable.  By  using  a 
flexible  cord,  the  lamp  in  Fig.  54  may  be  hung  outside  after 
the  box  is  opened  and  serve  as  the  source  to  be  used 
when  no  plates  are  exposed  to  light. 

Arrangement. — Darkrooms  may  be  quite  elaborate  and 
yet  be  very  inconvenient.  A  simple  arrangement  for  a 
small  outfit  is  shown  in  Fig.  55.  No  doors  are  needed  in 
this  case. 

Fixing  bath  and  supplies  are  to  be  kept  apart  from  de- 


X-RAY  PHYSICS 


125 


veloper  and  developing  supplies.  A  plain  open  shelf  is  used 
in  filling  envelopes,  etc.  Cassettes,  intensifying  screens, 
and  envelopes  may  be  kept  in  suitable  compartments  below. 
Plates  in  small  amounts  may  be  kept  in  compartments 
above  this  shelf.     An  inexpensive  arrangement  serving  all 

HYPO.    INLET    ^DEV. 


FIXING  SUP  PUBS 
SINK 


to 


o 

I 


DEVBLOP/NO 
SUPPLIES 


•30- 


PLATBS  BELOW- 

CASSETTES  AND 
ENVELOPES  BELOW- 


DRYING  RACK 


FAN 


PLATE 

LOAD- 
ING 
SHELF 


IN 


y-30- 


Fig.  55.     A  convenient  darkroom  arrangement. 


needs  is  shown  in  Fig.  56  for  holding  developer  tank,  fixing^ 
tank,  and  also  serving  as  a  washing  tank.  For  a  perma- 
nent installation  the  tank  may  be  lead-lined,  but  for  a 
semipermanent  wooden  tank  a  heavy  coating  of  water  and 
chemical-proof  paint  will  suffice.  In  warm  weather,  use  ice 
to  cool  bath,  and  do  not  dilute  developer. 

Ventilation. — Good  ventilation  is  essential  in  a  dark- 
room, not  alone  to  increase  the  efficiency  of  the  operator, 


126 


XL  S.  ARMY  X-RAY  MANUAL 


but  because  a  close,  musty  atmosphere  is  bad  for  the  sensi- 
tive emulsion.  When  a  new  room  is  designed,  the  matter 
is  quite  simple,  but  when  any  old  closet  is  regarded  as  good 


HYPO 


INLET 


D^V£L0P£R] 


Fig.  56.  Wooden  tank  to  permit  circulation  of  water  around  de- 
veloper and  fixer,  provides  for  rinsing  and  washing  films  or  plates 
at  same  temperature  throughout. 

enough  for  a  darkroom  it  is  quite  a  different  matter.     The 
important  point  to  be  kept  in  mind  is  that  air  must  be  let 


Bracket 


Fig.  57.     Simple  ventilator   for   darkroom.     All  inner   surfaces  to 
be  painted  red  or  black. 

in  and  out,  but  light  must  be  excluded.  Where  an  electric 
fan  can  be  used,  it  is  easy  to  accomplish  this  result.  Fig.  57 
shows  one  way.     The  fan  is  placed  in  a  box,  open  at  each 


X-RAY  PHYSICS  127 

end,  inserted  through  the  wall.  A  second  box  is  placed 
inside  the  room,  as  shown,  and  all  surfaces  are  painted  a  flat 
black.  Air  has  free  passage,  and  light  is  entirely  excluded. 
A  similar  arrangement  can  be  used  in  a  window,  either  with 
or  without  the  fan. 

Humidity. — Basement  darkrooms  are  often  very  damp 
in  summer  and  very  hot  in  winter.  The  best  work  cannot 
be  expected  under  these  conditions.  If  such  must  be  used, 
it  is  best  to  keep  unused  plates  elsewhere. 

Care  of  Utensils. — ^Absolute  cleanliness  is  essential  in 
darkroom  work.  Trays  not  in  use  are  best  kept  filled  with 
water.  Be  sure  that  no  acid  gets  into  the  developer.  Do  not 
use  developer  or  fixing  tanks  painted  inside  with  any  kind 
of  water-proof  paint. 

Supplies. — Be  careful  to  keep  all  containers  labeled,  so 
that  no  mistakes  are  likely  to  be  made.  Keep  hypo  and 
acids  away  from  developer  material.  Keep  chemicals  pro- 
tected from  moisture.  Remember  that  twice  the  weight  of 
crystals  must  be  used  as  in  case  of  ' '  dry ' '  materials. 

Marking  Negatives. — "Where  a  large  amount  of  radio- 
graphic work  is  done,  a  well-organized  record  system  is 
indispensable.  In  all  cases  the  record  should  show  in  some 
way  on  the  negative,  and  that  record  must  be  put  on  hefore 
the  plate  is  developed.  Lead  numbers  may  be  used,  and 
if  this  is  done  the  number  used  and  the  name  of  the  patient 
must  he  entered  on  a  suitable  card  or  hook  at  the  time  the 
exposure  is  made. 

If  numbers  are  not  used,  a  slip  showing  the  name  of 
the  patient  must  be  attached  to  the  cassette  or  envelope, 
and  the  darkroom  operator  should  always  write  the  name 
with  a  soft  pencil  on  one  corner  of  the  emulsion  hefore 
development. 

In  using  double-coated  film  care  should  be  taken  to  mark 
right  and  left,  as  one  cannot  tell  how  the  film  was  placed. 


128  U.  S.  ARMY  X-RAY  MANUAL 

The  X-Ray  Negative. — The  conditions  which  determine 
the  distribution  of  shadows  on  an  x-ray  negative  are  ex- 
tremely complex  and  vary  with  the  physical  condition,  age, 
and  weight  of  the  patient  even  without  any  reference  to 
pathological  conditions.  If  there  were  no  material  between 
the  target  and  the  photographic  emulsion,  there  would 
result,  upon  exposurt  and  development,  simply  a  uniform 
blackening  of  the  plate.  The  introduction  of  material  in 
the  path  of  the  radiation  between  the  target  and  the  plate 
results  in  absorption  and  scattering^  with  the  result  that 
portions  of  the  emulsion  are  protected  from  the  radiation, 
the  resulting  shadow  showing  as  a  white  or  lighter  area 
by  transmitted  light  through  the  negative.  The  amount 
of  radiation  failing  to  reach  any  area  of  the  plate  as 
compared  with  that  reaching  the  surface  of  the  obstructing 
body  depends  upon  two  things:  first  upon  the  relative 
physical  density  of  the  material  traversed  as  compared 
with  its  immediate  surroundings  and,  second,  upon  the 
distance  in  this  material  of  greater  or  lesser  density 
actually  traversed  by  the  rays.  As  an  illustration,  the 
shadow  cast  by  a  thin,  flat  bone,  placed  with  its  surface 
parallel  to  the  plate  will  show  little  contrast  as  compared 
with  the  shadow  of  the  surrounding  flesh,  whereas,  if 
placed  on  edge,  increasing  the  path  traversed  in  the  bone, 
there  will  be  marked  contrast. 

In  traversing  the  human  body  radiation  passes  through 
an  aggregate  made  up  of  portions  of  decidedly  different 
densities.  Each  of  these  portions  absorbs  the  radiation 
in  an  amount  depending  both  on  its  density  and  thick- 
ness. When  we  further  take  into  account  the  physical 
nature  of  the  action  of  the  photographic  plate  and  the 
different  absorbability  of  the  radiation  under  different 
conditions  of  tube,  we  may  easily  recognize  the  reason 
for  the  variety  of  negatives  which  it  is  possible  to  secure  of 


X-RAY  PHYSICS  129 

the  same  anatomical  region.  Inasmuch  as  our  diagnostic 
information  must  be  acquired  from  a  study  of  these  areas, 
we  must  not  forget  that  pathological  conditions  are  liable 
to  be  inferred  if  based  upon  doubtful  or  imperfect  data, 
and  while  Ave  can  not  at  present  lay  down  complete  rules 
for  the  guidance  of  the  roentgenologist  it  is  undoubtedly 
true  that  for  each  individual  area  there  is  a  combination 
of  factors  of  exposure,  penetration,  development,  and 
position,  that  would  give  the  best  diagnostic  plate. 

Consider  the  effect  of  varying  (1)  the  quality  of  the 
x-ray  beam,  (2)  the  time  of  exposure  when  making  a 
negative  of  any  particular  region.  Assuming  that  we  have 
proper  development  of  the  plate  after  exposure,  we  may 
note  that  if  the  tube  has  a  small  equivalent  gap  the  major- 
ity of  the  radiation  will  be  absorbed  completely  by  even 
thin  and  non-dense  portions  of  the  patient,  and  that  the 
exposure  in  order  to  have  any  effect  on  the  plate  must 
be  prolonged.  For  example,  in  the  case  of  the  hand,  such 
a  tube  with  proper  exposure  may  bring  out  wrinkles  or 
folds  in  the  flesh,  finger  nails,  and  a  very  slight  infiltra- 
tion in  the  soft  tissues,  and  only  by  prolonged  exposure 
can  even  a  moderate  definition  of  bones  be  observed. 
When  this  is  done  the  parts  of  the  negative  covered  by 
soft  tissue  are  greatly  overexposed.  If  the  spark  gap 
is  too  small  nothing  but  a  shadow  of  the  hand  such  as 
would  be  cast  by  ordinary  light  will  be  observed.  As  we 
change  the  spark  gap  with  a  suitable  time  of  exposure 
we  can  secure  quite  different  qualities  of  negative  and, 
with  a  moderate  gap  and  exposure,  fair  details  in  the 
bone  and  the  soft  tissue  may  be  observed,  but,  with 
longer  exposure,  portions  of  the  plate  beneath  the  thinner 
or  softer  regions  still  become  overexposed,  giving,  on  de- 
velopment, complete  blackness  without  details.  At  the 
same  time  the  outlines  of  the  thicker  portions  and  of  the 


130  U.  S.  ARMY  X-RAY  MANUAL 

bones  may  stand  out  very  clearly,  giving  almost  the  ap- 
pearance of  a  skeleton. 

If  the  spark  gap  is  made  too  high  the  radiation  reach- 
ing the  plate  may  be  only  modified  to  a  slightly  greater 
extent  by  the  bones  than  by  the  soft  tissue,  and  we  get  a 
characteristic  plate,  lacking  in  contrast,  which  is  generally 
described  by  the  term  ''flat."  In  an  extreme  case,  nearly 
all  of  the  radiation  might  pass  through  the  body  with 
only  a  trifling  amount  of  absorption,  and  there  would  be 
no  differentiation  with  reference  to  density  and  thickness 
upon  the  plate.  Consequently,  while  no  complete  guide 
can  be  given,  the  general  effect  of  increased  spark  gap  is 
to  reduce  the  contrast,  and  the  general  effect  of  increased 
exposure  with  moderate  gap  is  to  obliterate  the  details  in 
the  soft  tissue  or  thin  portions  with  an  increase  in  the 
visibility  of  the  shadows  cast  by  the  denser  or  thicker 
portions.  If,  for  example,  one  desires  a  study  of  the 
thoracic  vertebrae,  one  must  expect  that  portions  of  the 
plate  receiving  radiation  through  the  air-filled  lungs  will 
be  greatly  overexposed  and  will  indicate  no  shadows. 
With  a  softer  tube,  details  of  the  spine  and  ribs  will  be 
less  obvious,  while  the  linear  markings  in  the  chest  are 
rendered  visible.  It  naturally  follows  that  tube  condi- 
tion and  exposure  should  be  adapted  to  bring  out  the 
information  desired.  Mention  may  also  be  made  of  the 
fact  that  the  overexposed  and  denser  regions  may  fre- 
quently give  valuable  information  if  viewed  with  a  suffi- 
ciently strong  source  of  light,  while  a  thin  negative,  or 
those  portions  in  which  the  shadows  are  faint  and  the 
total  blackening  slight,  are  best  observed  in  weak  light. 

Inference  as  to  pathology  can  only  be  safely  made  when 
due  account  is  taken  of  the  variation  in  the  shadows  due 
to  normal  variation  in  human  anatomy  and  the  procedure 
followed  in  making  the  negative. 


X-RAY  PHYSICS 


131 


o 


O  Form  651 

Medical  Department,  U.  S.  Army 
(Revised  July  19,  1917) 

CLINICAL   RECORD 

RADIOGRAPHIC  REPORT 


Station. 

Date 

From 

To 


191 


Information   requested:. 


Clinical  diagnosis: 


.,  U.  S.  Army. 


Laboratory 

X-ray  findings: 


.,  191 


PLATE 


NUMBER  SIZE 


PART  DISPOSITION 


,  U.  S.  Army. 

SURNAME  OF  PATIENT 

CHRISTIAN  NAME 

RANK 

COMPANY 

REGIMENT  OR  STAFF  CORPS 

Fig.  58.     Eeeord  and  report  form  for  x-ray  examination    (actual 
size  3%   ins.  x  8  ins.). 


132  U.  S.  ARMY  X-EAY  MANUAL 

Records. — The  importance  of  the  correct  recording  of 
all  information  obtained  by  means  of  the  x-ray  cannot  be 
overestimated.  Of  equal  or  greater  importance  is  the 
establishment  of  the  identity  of  the  patient  examined  with 
the  x-ray  findings.  Furthermore,  the  identity  of  the  side 
examined  should  be  verified  in  every  case. 

That  the  x-ray  findings  are  brought  to  the  attention  of 
the  attending  surgeon  is  essential.  An  actual  conference 
between  the  surgeon  and  the  roentgenologist  is  very  desir- 
able in  order  that  each  may  have  the  advantage  of  the 
other's  personal  opinion. 

Each  plate  should,  therefore,  be  marked  for  identifica- 
tion by  means  of  opaque  markers  and  the  corresponding 
information  immediately  recorded  on  the  blanks  provided 
for  this  purpose. 

Form  551  Medical  Department,  U.  S.  Army  (Revised 
July  19,  1917),  will  be  used  for  this  purpose.  Fig".  58.  In 
all  cases  a  duplicate  of  this  report  should  be  retained. 


LABORATORY  EXPERIMENTS 

Laboratory  Instruction  in  Preparation  for  Roentgenol- 
ogy.— The  following  experiments  are  part  of  a  series  used 
in  the  laboratory  course.  They  were  easier  of  execution 
in  the  laboratory  in  which  they  were  devised,  and  results 
were  more  conclusive,  on  account  of  having  a  very  good  high 
tension  voltmeter  so  that  tube  voltage  measurements  could 
be  accurately  and  quickly  made. 

The  objects  of  such  experiments  are: 

1.  To  give  practice  in  quickly  adjusting  machine  and 
tubes  to  any  desired  current  and  voltage. 

2.  To  impress  on  the  mind  of  the  student  the  relation 
of  the  fundamental  factors — voltage,  current,  distance  and 
time — to  the  nature  of  image  desired. 

3.  To  assure  the  operator  that  results  are  reproduci- 
ble if  conditions  are  right. 

4.  To  show  some  of  the  pitfalls  usually  encountered 
and  to  avoid  having  to  acquire  experience  on  the  living 
patient. 

While  at  first  such  experiments  may  seem  very  time- 
consuming,  experience  has  shown  that  the  skill  and  con- 
fidence acquired  will  much  more  than  repay  it  in  a  com- 
paratively short  time. 

New  students,  and  even  those  of  some  experience,  are 
likely  to  have  trouble  in  handling  the  apparatus  if  it  has 
many  unusual  details.  They  should,  therefore,  read  such 
paragraphs  of  the  manual  as  deal  with  the  elementary 
principles,  before  starting  experimental  work. 

133 


134  U.  S.  ARMY  X-RAY  IMANUAL 

The  Coolidge  tube  is  used  in  these  experiments  on 
account  of  its  easy  adjustment.  Experience  indicates  that 
when  taking  the  same  current  at  the  same  voltage  all  tubes 
give  very  much  the  same  density  of  negatives,  so  that  ex- 
posures learned  on  the  Coolidge  tube  apply  to  the  gas  tube 
in  so  far  as  the  conditions  can  be  made  the  same. 

Experience  in  the  training  of  a  considerable  number 
of  students  has  clearly  shown  that  the  handling  of  x-ray 
apparatus  cannot  he  learned  by  seeing  some  one  else  do  it. 
Only  when  the  students  have  repeatedly  carried  on  the 
actual  manipulations  themselves,  time  after  time,  can  they 
be  depended  upon  under  working  pressure.  Much  time 
is  lost  in  not  knowing  just  what  exposures  should  be  given 
and  the  test  plates  described  are  excellent  checks  on  accu- 
racy and  rapidity.  The  student  should  be  well  drilled  in 
quickly  setting  the  tube  and  control  for  definite  readings. 
In  the  study  of  plates  as  well  as  in  the  technical  work 
the  student  should  do  absolutely  individual  and  independ- 
ent work. 

Instruction  Unit. — A  small  instruction  unit  has  been 
devised  to  clearly  set  forth  the  basic  principles  of  the  large 
x-ray  machines  and  to  avoid  unnecessarily  tieing  up  ex- 
pensive equipment  for  elementary  instruction  purposes. 
This  machine  is  composed  of  only  the  customary  elements 
and  these  are  arranged  on  an  ordinary  pine  table  so  that 
all  parts  and  all  wires  are  completely  in  view  and  readily 
accessible.  For  instruction  purposes  high  power  is  un- 
necessary, and  a  small  transformer  is  ample  for  the  pur- 
pose. With  the  transformer  used,  loads  up  to  5-inch  gap, 
30  ma.,  may  be  safely  drawn  for  test  plate  and  other 
experimental  work.  The  autotransformer,  rheostat,  fila- 
ment transformer,  timer,  etc.,  are  standard  parts  as  used 
on  the  large  machines,  so  that  the  student  may  become 
familiar  with  their  function  and  operation. 


LABORATORY  EXPERIMENTS 


135 


It  is  intended  to  have  the  machine  as  simple  as  it  is 
possible  to  make  it,  and  to  this  end  the  various  circuits 
are  distinguished  from  each  other  by  the  color  of  wire 
used.  Thus,  the  main  primary  circuit  is  black,  the  motor 
circuit  is  blue,  the  Coolidge  filament  primary  is  red,  and 
the  remote  control  circuit  is  green.  Even  to  a  beginning 
student  the  circuits  stand  out  separate  and  distinct,  and 
the  machine  appears  organized  and  rational  rather  than 

fsr| 


\^ 


Main  Primary  Circuit 
Auto- trans: 


SO 


Fig.  59.     Diagram    of    connections   of    instruction   unit. 


a  hopeless  maze  of  wiring.  Fig.  59  shows  the  diagram 
of  connections  and  Fig.  60  shows  the  machine  itself.  Su- 
perfluous parts  have  been  eliminated  and  the  features 
shown  are  so  fundamental  that  each  student  should  be 
able  to  wire  up  the  complete  machine  as  part  of  his  labora- 
tory work. 

Aside  from  giving  a  knowledge  of  the  electrical  elements 
of  x-ray  machines,  the  unit  is  used  to  give  considerable 
practice  in  setting  for  any  desired  tube  voltage  and  milli- 
amperage,  in  operating  when  failure  of  some  non-essential 


136 


U.  S.  ARMY  X-RAY  MANUAL 


element  occurs,  and  in  studying  the  physical  properties  of 
the  x-rays. 

Test  Plates. — The  quantitative  measurement  of  x-ray 
radiation  has  proved  a  difficult  matter,  but  for  our  pur- 


FiG.  60.     Machine  used   for   instruction  purposes.     All  parts  and 
wiring  are  openly  displayed. 


pose  the   photographic  effect  is  sufficiently  accurate  and 
determines  the  usefulness  of  the  rays  in  practice. 

We  cannot  readily  compare  the  radiation  received  on 
two  spots  of  unequal  density.  Under  any  conditions  of 
operation,  however,  if  two  portions  of  a  photographic 
plate  subjected  to  radiation  and  given  the  same  develop- 


LABORATORY  EXPERIMENTS  137 

ment  have  equivalent  blackening:  we  may  say  that  the 
two  parts  received  the  same  quantity  of  photographically 
effective  radiation  per  unit  area,  or  that  they  had  the 
same  exposure,  in  which  case  exposure  does  not  mean 
time  alone. 

If  a  spot  exposed  1  second  and  a  spot  exposed  2  sec- 
onds are  of  equal  darkness,  then  we  can  say  that  the 
first  spot  was  subjected  to  radiation  twice  as  intense  as 
the  second,  for  it  took  only  half  as  long  to  give  equal 
effect.  The  spots  should  not  be  heavily  overexposed  or 
over-developed,  for  it  is  in  the  medium  gray  tones  that 
distinctions  in  density  are  most  accurately  and  easily 
made. 

A  5  X  7  plate  is  cased  in  the  usual  envelope  or  in  a 
light-tight  plate  holder.  The  student's  name,  laboratory 
number  and  the  number  of  the  experiment  should  be 
written  on  the  emulsion  side  of  the  plate  with  soft  lead 
pencil  when  loading.  A  5  x  7  lead  plate  with  ten  1- 
inch  holes  is  used  to  protect  the  body  of  the  plate  from 
radiation  and  all  holes  except  the  one  spot  to  be  ex- 
posed are  covered  with  sheet  lead.  Expose  the  test  spots 
in  proper  sec[uence  down  the  two  rows  of  holes,  and  place 
a  small  metallic  marker  on  spot  No.  1  during  exposure  to 
identif}^  it  later. 

In  using  a  timer  do  not  vary  its  settings,  as  the  scales 
are  rarely  calibrated  with  sufficient  accuracy.  Keep  the 
timer  set  at  0.1  second  and  repeat  the  exposure  the  re- 
quired number  of  times.  If  the  machine  is  not  equipped 
with  a  timer  capable  of  conveniently  repeating  1/10  sec- 
ond exposures,  time  with  a  stop  watch  or  by  counting 
to  full  seconds  instead  of  tenths.  Increase  considerably 
the  target-plate  distance  in  this  case,  if  possible. 

Do  not   develop   test   plates  too   far.   Stop   as  soon   as 


138  U.  S.  ARMY  X-RAY  MANUAL 

spots  Nos.  1  to  5  show  fairly  well  on  the  back  of  the 
plate.  If  the  settings  have  been  carefully  made  and  ex- 
posures accurately  timed,  spots  Nos.  1  to  5  should  be  ap- 
proximately equal  in  density  and  Nos.  6  to  10  should 
run  successively  darker  or  lighter  as  the  case  may  be. 

"When  the  finished  plates  are  dry  the  spots  should  be 
numbered  and  all  exposure  data  written  on  the  emulsion 
side  of  the  plate  with  pen  and  ink.  The  plate  should 
then  be  turned  in  for  inspection  and  credit. 

Before  commencing  work  read  and  understand  the  gen- 
eral instructions  and  precautions  on  page  20. 

Distance-Time  Relation— Inverse  Square  Law. 

Test  Plate  1. — The  x-rays  travel  out  from  the  electron 
impact  point  on  the  target  in  straight  lines,  so  that  the 
amount  in  a  cone  of  a  given  angle  is  spread  over  an  in- 
creasing base  area  as  we  recede  from  the  tube.  A  plate  of 
fixed  size  intercepts  more  radiation  in  a  given  time  when 
close  to  the  source.  If  we  move  a  plate  to  double  its  origi- 
nal distance  from  the  target,  the  radiation  received  per  sec- 
ond on  a  given  area  will  be  only  14  as  great;  at  ten  times 
the  distance,  1/100  as  great.  In  order  to  secure  the  same 
radiation  effect,  the  time  of  reception  must  be  increased 
four-fold  in  the  first  case  and  one  hundred  fold  in  the 
latter. 

For  constant  tube  current  and  voltage  the  plate  black- 
ening will  be  unchanged  if  we  keep  ^— con- 
distance  ^ 

stant  for  all  exposures. 

Set  for  10  ma.  at  a  3-inch  spark  gap  and  expose  spots 
as  shown  below.  Or  the  bedside  unit  may  be  used,  ex- 
posing seconds  instead  of  tenths. 


LABORATORY  EXPERIMENTS  139 

Spot  Spot 


Xo. 

Distance 

Time 

No. 

Distance 

Time 

1 

10  in. 

.1  sec. 

6 

10  in. 

.  .1  sec 

2 

20" 

.4  " 

7 

20" 

.1  " 

3 

30" 

.9  " 

8 

30" 

.1  " 

4 

40" 

1.6  " 

9 

40" 

.1  " 

5 

50" 

2.5  " 

10 

50" 

.1  " 

In  the  first  row  of  spots  we  have  compensated  for  the 
change  in  distance  b}^  a  proper  corresponding  change  in 
time,  so  these  spots  will  have  the  same  density.  In  the 
second  row  we  have  made  no  such  compensation  and 
the  spots  will  not  be  equally  dark.  The  target-plate  dis- 
tances ordinarily  used  in  radiographic  work  vary  from 
15  to  36  inches.  The  sharpness  of  the  radiograph  increases 
with  greater  distance,  but  longer  time  is  required.  As- 
suming that  1  second  is  the  correct  exposure  for  a  given 
object  at  20  inches,  plot  a  curve  on  cross  section  paper 
showing  time  required  at  various  distances  up  to  36  inches 
to  give  the  same  density  of  plate. 

Current-Time  Relation. 

Test  Plate  2. — The  x-ray  energy  on  a  given  plate  area 
per  unit  time  when  the  voltage  is  constant  and  the  target- 
plate  distance  is  fixed,  increases  in  direct  proportion  to  the 
current.  Thus,  we  get  the  same  radiation  in  half  the  time 
when  using  50  ma.  as  when  using  25  ma.  Or,  for  equal 
photographic  effect  the  product  of  milliamperes  and  sec- 
onds must  remain  constant. 

To  test  this  law  expose  a  test  plate  as  follows : 

Voltage  constant  at  a  4-inch  gap. 

Target-plate  distance  constant  at  30  inches. 


140  U.  S.  AR]\1Y  X-RAY  MANUAL 


5pot 

;     Current 

Time 

Spot 

Current 

Tim 

1 

5  nia. 

1.2  sec. 

6 

5  ma. 

1.2  se 

2 

10    '' 

.6  '^ 

7 

10    '' 

1.2  '' 

3 

15    '' 

.4  '' 

8 

15    ^^ 

1.2  '' 

4 

20    '' 

.3  " 

9 

20    '' 

1.2  '' 

5 

30    '' 

.2  '^ 

10 

30    '' 

1.2  ^' 

Notice  that  we  have  compensated  by  a  decrease  in  time 
for  the  increase  in  current  in  the  first  row  and  that  the 
second  row  is  uncompensated. 

Voltage-Time  Relation. 

Test  Plate  3. — The  radiation  leaving  a  given  target  as 
registered  by  a  photographic  plate  is  not  fixed  by  the 
amount  of  current  alone,  but  varies  greatly  with  the  drop 
in  voltage  through  the  tube.  In  fact,  it  increases  very 
nearly  in  proportion  to  the  square  of  the  voltage.  This 
means  that  on  doubling  the  voltage,  all  other  factors  re- 
maining unchanged,  we  get  four  times  the  photographi- 
cally effective  radiation  per  second  and  would  then  need 
but  one-fourth  the  exposure  time. 

"With  an  electrostatic  high  tension  voltmeter  it  is  easy 
to  read  voltage  directly,  but  this  instrument  is  not  ordi- 
narily available.  The  so-called  primary  "kilovoltmeters" 
with  which  many  machines  are  equipped  are  not  reliable 
indicators  of  secondary  voltage,  as  they  do  not  read  the 
same  for  the  same  secondary  voltage  under  different  loads 
on  the  transformer.  Parallel  sparking  distance  between 
blunt  points  is  our  best  available  guide  to  tube  voltage. 
The  relation  between  spark  length  and  kilovolts  is  shown 
in  Fig.  12.     It  may  be  considered  as  reasonably  true  that 


LABORATORY  EXPERIMENTS 


141 


under  average  conditions  the  kilovoltage  is  ten  times  the 
spark  in  inches  plus  ten,  i.  e.,  3-inch  gap  =  40  kv. ;  5V2-inch 
gap  =:  65  kv.,  etc. 

Exposures  are  to  be  made  as  follows: 
Current  constant  at  5  ma. 
Distance  constant  at  25  inches. 


Spot       Gap 

Time 

Spot 

Gap 

Time 

1       2''   (30  kv.) 

1.6  sec. 

6 

2''   (30  kv.; 

)       1.6  sec 

2       3"   (40    "  ) 

.9    " 

7 

3"   (40    "  ] 

)       1.6    " 

3       4''   (50    "  )■ 

Q^<C 

8 

4"   (50    " 

)       1.6    '' 

4       5"   (60    "  ) 

.4    " 

9 

5"   (60    "  ] 

)       1.6    '' 

5       6"   (70    "  ) 

.3*'' 

10 

6"   (70    " 

)       1.6    '' 

*  These  figures  are  fair  approximations  to  the  exact  values. 

The  equality  of  density  of  numbers  1  to  5  as  well  as 
the  great  densit}^  difference  of  numbers  6  to  10  illustrate 
well  the  effect  of  increased  voltage. 

It  must  not  be  assumed  that  the  quantity  of  radiation 
alone  varies  with,  the  voltage  at  constant  current  and  time. 
The  ability  to  pass  through  material  also  increases  to  a 
'  great  extent  at  higher  voltage.  The  quality  of  negatives  of 
the  same  average  density  made  at  high  and  at  low  voltage 
is  quite  different  and  a  voltage  (penetration)  suitable  for 
the  case  in  hand  should  be  chosen  if  the  best  results  are  to 
be  secured. 


Summary  of  the  Preceding  Relations 

Test  Plate  4. — Formulating  the  experience  derived  from 
the  preceding  experiments,  we  may  conclude  that  for  a 
given  tube  and  machine — i.  e..  a  fixed  wave  form,  fre- 
quency, target,  and  absorbing  glass  wall — we  may  regulate 


142  U.  S.  ARMY  X-RAY  JMANUAL 

the  exposure,  when  no  absorbing  material  is  traversed,  by 
control  of  (a)  current,  (b)  voltage,  (c)  time,  (d)  dis- 
tance. 

Expressed  in  algebraic  form,  the  photographic  effect  E 
is  given  by 

K  X  Current  x  (Voltage)-  x  Time 

jjj  =^  . . 

(Distance)^ 
where  K  may  change  for  various  targets,  glass  walls,  or 
wave  form,  but  is  fixed  for  a  given  tube  and  outfit.  If  this 
is  true,  one  can  readily  compute  from  one  set  of  condi- 
tions the  length  of  time  under  other  conditions  that  will 
give  the  same  plate  density. 

To  calculate  the  time  for  a  given  exposure  use  simple 
approximate  methods,  not  long  and  involved  computations. 
Thus,  if  a  case  is  given  as  follows: 
Exposure  1 : 

50   ma. — 5-inch   gap — 18    inches — 4   seconds. 
Exposure  2 : 

15   ma. — 4-inch   gap — 27   inches — time   =    ? 
Decrease  in  current  increases  time  10/3  times. 
Increase  in  distance  increases  time  9/4  times. 
Decrease  in  gap  increases  time  25/16  =  3/2 
Then  the  required  time  is 


5 


--x  —  X  -  X  -  =  45  seconds. 


Start  with  4-inch  gap  10  ma.  20-inch  target-plate  dis- 
tance, and  .2  sec.  Calculate  and  expose  11  spots  so  as  to 
vary  two  or  three  of  the  above  factors  each  time,  but  keep 

(4)"  X  10  x  .2 

^  constant,    £'= ~  —-  .08  arbitrary  units  for  spot 

(20)' 


LABORATORY  EXPERIMENTS 


143 


No.  1.  Thus,  if  current  is  raised  to  30  ma., 
this  increase  would  give  a  time  y,^  as  great;  but  if 
the  distance  is  raised  to  30  inches  the  greater  distance  would 
require  a  time  9/4  as  great.  Hence  the  correct  time  with 
the  combined  change  is  .2  x  1/3  x  9/4  =  .15. 

Do  not  work  below  a  2-inch  gap  on  account  of  the  absorp- 
tion of  the  glass  walls  of  the  tube,  or  on  the  small  instruc- 
tion units  above  5  ma.  on  a  6-inch  gap  or  above  30  ma.  on 
a  smaller  gap. 

Use  a  variety  of  control  buttons,  and  where  the  timer 
will  not  give  exact  results,  get  as  near  as  possible  or  vary 
one  or  more  factors  to  get  exact  tenths.  The  timer  will 
not  give  smaller  fractions  with  any  considerable  accuracy. 

The  exposures  are  to  'be  computed  before  commg  to  the 
laboratory. 

Enter  your  results  as  follows : 


No, 

MA. 

Gap. 

Distance 

Time 

1 

10 

4// 

20'' 

.2  sec. 

2 

5 

0'' 

25'' 

9 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

144  U.  S.  ARMY  X-RAY  MANUAL 

If  correctly  done,  no  variation  in  darkening  will  be  ob- 
served. 

Change  IN  Time  of  Exposure  with  Thickness 

Test  Plate  5. — Exposure  Factor.  Find  by  trial  the  ra- 
tio of  the  time  required  to  get  the  same  density  through 
one  layer  of  a  paraffin  as  when  no  absorber  is  present.  To 
do  this,  expose  a  plate,  using  a  machine  setting  of  10  ma., 
3-inch  gap ;  or  use  the  bedside  unit,  exposing  seconds  in- 
stead of  tenths  and  giving  the  plate  much  shorter  develop- 
ment.    Use  17-inch  distance  for  all  spots. 

Spot  Layers  of    Time     Spot.  Layers  of    Time 

No.  Paraffin  No.  Paraffin 


1 

0 

.1 

6 

1 

.4 

2 

0 

.2 

7 

1 

.5 

3 

0 

.3 

8 

1 

.6 

4 

1 

.2 

9 

1 

.7 

5 

1 

.3 

10 

1 

.8 

When  the  plate  is  developed  compare  other  spots  with 
Nos.  1,  2  and  3,  and  select  the  pair  that  comes  closest  to  an 
exact  match  in  density.  If,  for  example,  spots  No.  1  and 
5  are  equally  dark,  the  exposure  factor  is  determined  by 
the  ratio  of  the  time  of  exposure  used — in  this  instance,  3. 

This  factor  can  be  checked  by  comparing  spots  No.  2  and 
8,  which  should  match  if  the  factor  is  3. 

A  method  similar  to  this  can  be  used  to  obtain  the  speed 
ratio  of  intensifying  screens,  exposing  part  of  a  plate  with 
a  screen  and  part  without,  as  suggested  elsewhere  in  the 
manual.  Fig.  52,  page  114. 

Absorption  of  rays  and  scattering  gives  an  explanation 
of  the  great  increase  in  time  of  exposure  with  increasing 


LABORATORY  EXPERIMENTS 


145 


thickness  of  absorbing  layer.  Thus,  if  experiment  shows 
that  a  certain  thickness  of  a  given  material  will  reduce 
the  emerging  radiation  to  3/5  the  incident,  then  a  spot  ex- 
posed through  this  layer  will  require  5/3  the  time  for  the 
same  photographic  density  as  the  uncovered  portion  of  the 
jjlate  would  require.  For  two  such  layers  25/9  the  orig- 
inal time  W'ill  be  required,  for  three  layers  125/27,  etc. 


PLATE.^  ^     S    ^ 
Fig.  61.     Effect    of    scattering    on  undercutting  of  image. 

{Test  Plate  6).  Using  the  factor  obtained  from  Test 
Plate  5  and  the  law  indicated  above,  calculate  proper  ex- 
posure times  and  expose  the  plate  as  follows: 

Machine  setting  constant  at  10  ma.,  3-inch  gap,  30-inch 
distance;  or  use  the  bedside  unit,  if  it  was  used  for 
Test  Plate  5,  again  exposing  seconds  instead  of  tenths  and 
giving  the  plate  short  development. 


Spot 

Layer  of 

Time 

Spot 

Layer  of 

Tim 

No. 

Paraffin 

No. 

Paraffin 

1 

0 

.3 

6, 

0 

.a 

2 

1 

^  , 

7 

1 

.3 

3 

2 

•  • 

8 

2 

.3 

4 

3 

•  • 

9 

3 

.3 

5 

4 

10 

4 

.3 

146  U.  S.  ARMY  X-RAY  MANUAL 

The  time  for  proper  exposure  in  order  to  get  the  best 
plate  does  not  work  out  from  the  simple  law  of  absorp- 
tion. The  reason  is  clear  when  we  consider  scattering 
in  tissue.  Let  AB,  in  Fig.  61,  be  a  small  object  in  the 
body,  relatively  opaque  to  x-rays.  If  there  were  no  scat- 
tering, the  area  S  would  be  protected  from  radiation  by  an 
amount  fixed  by  the  increase  in  absorption  of  AB  over  that 
of  an  equal  amount  of  tissue.  Thus,  if  volume  represented 
by  1,  2,  3,  4  would  absorb  95  per  cent  when  AB  is  absent, 
then  if  the  object  were  entirely  opaque  it  could  only  reduce 
exposure  by  5  per  cent  of  that  adjacent  to  it.  In  addition, 
all  the  shaded  portions  of  the  figure  are  sending  scattered 
radiation  to  8  in  proportion  to  what  each  point  receives. 
To  reduce  this  scattering  as  much  as  possible  no  more  of 
the  body  should  be  exposed  than  is  necessary,  and  condi- 
tions maintained  to  give  as  high  contrast  as  possible.  The 
best  plates  of  thick  parts  are  rarely  of  high  density  as 
compared  with  those  of  extremities.  Contrast  is  always 
better  when  the  gap  is  made  as  low  as  possible,  consistent 
with  other  operating  conditions. 


The  Benoist  Penetrometer 

Test  Plate  7. — X-rays  are^caused  by  the  violent  change 
in  the  speed  of  electrons,  and  the  quantity  and  quality  of 
the  beam  will  depend  on  the  number  of  electrons  involved, 
their  speed,  and  the  suddenness  of  their  stop.  By  quality, 
we  should  specify  the  relative  intensity  of  each  wave 
length.  As  the  operating  voltage  is  increased,  there  is  a 
greawncrease  in  the  electron  velocjtv.  Thus  Ev  =  % 
MY^,  where  E  is  the  electronic  charge,  v  the  voltage,  M 
the  mass  of  the  electron,  and  Y  its  speed. 


LABORATORY  EXPERIMENTS 


147 


There  is  no  way  of  easily  analyzing  a  beam  and  so  the 
ability  of  the  shorter  waves  to  pass  through  material  is 
used  to  give  a  rough  idea  of  the  quality.  This  penetration 
is  only  approximately  indicated  by  a  penetrometer.  The 
Benoist  penetrometer  may  be  used  to  test  out  exposures  and 
to  secure  a  more  accurate  knowledge  of  the  factors  govern- 
ing plate  density  than  can  be  easih'  acquired  otherwise. 

Use  a  lead  cover  having  twelve  holes  to  take  a  fairly 
large  penetrometer.  Use  sheet  lead  to  cover  parts  of  plates 
not  being  exposed.  Remove  the  holder  from  the  table  and 
cover  all  portions  while  adjustments  are  made,  in  order  to 
avoid  fogging.  Take  considerable  care  in  adjusting  the 
tube,  and  note  carefully  the  exposures  specified.  Study 
your  plate  and  see  how  it  checks  out  with  the  computed 
times  for  equality  of  density  as  far  as  the  blackening  under 
the  silver  is  concerned. 

Silver  is  approximately  a  non-selective  absorber  for  the 
range  of  wave  lengths  used  in  practice,  while  the  aluminum 
absorbs  "soft"  rays  in  excess.  Read  the  "hardness"  by 
noting  the  number  of  the  aluminum  sector  that  gives  the 
same  photographic  density  as  the  silver.  That  sector  giv- 
ing the  highest  plate  density  is  called  No.  1,  and  the  others 
number  consecutively.  Discuss  carefully  the  difference  seen 
in  the  negative.  Make  the  following  exposures  with  fairly 
careful  settings. 

Target-plate  distance,  15  inches. 


Row  1 

Row  2 

Row  3 

Ma. 

Gap 

Time 

Ma. 

Gap 

Time 

Ma. 

Gap 

Time 

10 

2'' 

1.2 

10 

2" 

1.2 

10 

2'' 

1.2 

15 

2" 

•     .8 

10 

3" 

.7 

15 

3" 

.4 

20 

2" 

.6 

10 

4" 

.4 

20 

4" 

.2 

25 

2" 

.5 

10 

5" 

.3 

25 

5'' 

.1 

148  U.  S.  ARMY  X-RAY  MANUAL 

Tabulate  the  Benoist  hardness  and  voltmeter  readings, 
also  plot  on  cross  section  paper.  What  relation  exists  in 
the  incident  radiation  among  the  above  exposures  ? 

The  longer  wave  lengths  are  absorbed  in  excess,  and 
the  remainder  of  the  beam  as  transmitted  contains  an  ex- 
cess of  short  waves.    Such  a  beam  is  said  to  be  filtered. 

Note. — The  Benoist  penetrometer  is  not  a  very  useful 
or  reliable  guide  as  to  tube  quality — not  nearly  so  satis- 
factory in  transformer  operation  as  spark  gap ;  but  it  does 
serve  to  give  an  idea  of  penetration  difference  if  one  is 
sure  that  the  same  quantity  falls  on  the  instrument  in  each 
case. 


NEW    APPARATUS 

In  the  following  pages  of  this  manual  there  will  be  de- 
scribed some  new  apparatus  and  appliances  which  have 
been  developed  with  advice  of  many  roentgenologists  and 
surgeons  with  the  sole  intent  of  aiding  the  service.  This 
apparatus  was  not  designed  to  secure  novelty,  or  simply  to 
be  different  from  other  devices,  but  with  a  view  of  secur- 
ing, first,  simplicity  and  convenience,  second,  elimination 
of  error  and  unnecessary  steps  and,  third,  to  secure  manu- 
facture at  such  a  rate  as  will  enable  the  product  to  be 
used  at  the  earliest  possible  moment. 

It  is  urgently  desired  that  every  roentgenologist  to  whom 
this  apparatus  is  delivered  take  the  time  necessary  to  study 
it  over  and  to  acquire,  at  least  initially,  the  point  of  view  of 
the  designer.  Simply  because  some  particular  feature  with 
which  he  has  been  familiar,  and  which  has  been  more  or 
less  fashionable  among  roentgenologists,  is  missing,  is  not 
a  sufficient  excuse  for  general  condemnation  or  rejection 
of  the  standard  outfit.  After  making  sure  that  the  appara- 
tus is  properly  assembled  every  operator  should  go  rapidly 
through  the  steps  in  handling  it  with  a  view  to  smoother 
operation  and  to  saving  time.  The  instructions  which  are 
given  may  serve  as  a  basis  for  such  self -drill,  and  it  is  of 
course  to  be  expected  that  many  modifications  of  procedure 
and  inexpensive  additions  to  equipment  may  readily  be 
provided  on  the  initiative  of  the  operating  roentgenologist. 

Every  roentgenologist  is  advised  to  file  and  retain  all 
copies  of  instructions  and  catalogues  or  blue  prints  fur- 

149 


150 


U.  S.  ARMY  X-RAY  MANUAL 


nished  with  the  outfit  by  the  manufacturer.  These  may 
be  of  considerable  assistance  in  case  of  breakdown  or 
damage,  even  though  the  directions,  in  some  measure,  do 
not  correspond  with  the  general  instructions  given  in  this 
manual. 


Fig.  62.     Standard  U.  S.  Army  x-ray  table  with  insulating  masts 
and  holders  and  box  for  standard  type  tube. 


Army  X-Ray  Table. — The  standard  x-ray  table  consists 
of  the  following  principal  parts:     (Figs.  62  and  63.) 

1.  Two  aluminum  end  castings. 

2.  Three  steel  side  rails. 

3.  A  rectangular  frame  as  a  tube-box  cradle. 

4.  A  lead-covered  tube  box. 

5.  A  special  detachable  shutter. 


9. 
10. 


NEW  APPARATUS 


151 


A  rectangular  wooden  frame  supporting  a  stretcher 

type  top. 

An  operating  switch. 

A  special  screen  carrier. 

High  tension  vertical  insulators. 

A  tube  holder  for  working  above  the  table. 


Fig.  63.  Standard  U.  S.  Army  x-ray  table  complete  with  box  for 
radiator  type  tube. 

When  the  table  is  to  be  used  with  the  portable  outfit  a 
tube  box  designed  for  the  radiator  type  of  tube  must  be 
used.  For  the  usual  base  hospital  outfit,  a  tube  box  taking 
the  standard  tubes  is  supplied.  In  the  former  the  high 
tension  insulators  both  enter  the  same  end  of  the  box,  in 
the  latter  they  enter  at  opposite  ends.  Any  or  all  of  num- 
bers 8,  9j  and  10  may  be  omitted  in  special  cases. 


152 


U.  S.  ARMY  X-RAY  MANUAL 


In  the  description  following,  numbers  in  parenthesis 
refer  to  the  figures  in  the  text,  not  to  manufacturers'  stock 
or  replacement  numbers. 

End  Castings. —  (Fig.  64)  The  end  castings  (41)  have 
four  slots  (42)  on  each  side.  These  take  the  ends  of 
the  steel  side  rails.  Two  rails  (45)  are  used  on  the  opera- 
tor's side  of  the  table  and  one  on  the  other  side.  When 
using  the  regular  top  the  rails  should  be  placed  in  the 


Fig.  64.     Framework  of  standard  army  x-ray  table  and  operating 
pull  switch  (49). 


upper  of  each  pair  of  slots.  If  one  must  use  an  army  lit- 
ter, use  the  lower  slots.  Holes  are  provided  to  mount  the 
masts  for  overhead  work. 

Rails. —  (Fig.  64)  The  round  rails  have  tightening' 
screws  (48)  with  permanently  attached  handles.  Sliding 
on  one  of  these  rails  are  three  rings  (46,  85,  95).  The  one 
at  the  left  serves  to  lock  the  screen  carriage,  the  center  one 
locks  the  tube  box  against  longitudinal  run  and  also  may  be 
used  to  secure  a  tube  shift  of  either  10  or  15  centimeters. 
The  right-hand  ring  serves  in  measuring  any  desired  tube 


NEW  APPARATUS 


153 


shift.     These  should  always  be  placed  on  the  rail  in  the 
order  shown. 

Cradle. —  (Fig.  Q^)  The  cradle  has  three  roller-lDear- 
ing  wheels  (81)  to  give  longitudinal  run  on  the  side 
rails.  The  single  roller  on  the  right  has  a  screw  brake 
to  be  used  when  lifting  the  box.     The  cross  piece  on  the 


Fig.  65.     Details  of  tube  box,  cradle  and  shutter,  standard  army 
x-ray  table. 


operator's  side  carries  a  tube  box  brake  (57)  for  lateral 
locking  when  in  use,  also  three  stops  for  tube  shift  meas- 
urement. The  one  near  the  center  (84)  is  permanently 
attached,  as  is  also  the  one  at  the  right  (82).  The  third 
(83)  is  placed  close  to  the  roller  and  when  the  ring  (85). 
is  placed  between  (83)  and  (84)  we  have  a  15  cm.  shift; 
by  changing  the  position  of  the  screw  (57)  of  the  cross 
run  brake,  we  may  secure  a  10  cm.  shift  between  stop  (84) 
and  the  stop   (80)   on  the  brake. 


154 


U.  S.  ARIMY  X-RAY  MANUAL 


Box. —  (Figs.  65,  66  and  67)  Two  types  of  box  are 
built,  one  for  use  with  the  radiator  type  Coolidge  tube,  the 
other  for  the  ordinary  tubes.  The  former  must  he  used  on 
all  portable  outfits,  the  latter  is  known  as  the  base  hospital 
tube  box.  In  the  portable  box  both  insulators  enter  at 
one  end.    In  the  base  hospital  one  is  placed  at  each  end. 

In  both  boxes  the  tube  mount  slides  into  the  box  at  the 


Fig.  66.     Mounting  of  standard  type  tube  in  army  x-ray  table. 


end.  Fig.  67  shows  the  mounting  with  insulators  for  the 
radiator  type  of  tube.  The  partition  (62-63)  is  covered 
with  lead  rubber  and  the  upper  portion  is  removable  for 
insertion  of  the  tube.  The  tube  may  be  raised  or  lowered 
or  shifted  longitudinally  for  centering.  The  insulating 
posts  with  the  transverse  wire  (69)  are  used  in  adjusting 
the  target  position.  All  connections  to  the  tube  are  to  be 
made  before  inserting  the  slide  in  the  box. 

Shutter. —  (Fig.    65)    The    shutter    has    double    slides; 


NEW  APPARATUS 


155 


one  pair  controlled  by  the  outer  knob  (74)  gives  a  dia- 
mond-shaped opening";  that  controlled  by  the  inner  knob 
(75)  gives  a  slit  parallel  to  the  length  of  the  table.  The 
shutter  is  attached  to  the  box  by  the  pins  (56)  and  clamps 
(71),  as  shown,  and  these  must  be  closed  before  using. 


Fig.  67.     Tube  box  and  mount  for   radiator   type  tube,   standard 
army  x-ray  table. 


Top. —  (Fig.  64)  The  rectangular  frame  (30)  is  nar- 
rower than  the  supporting  ends  of  the  table,  permitting  a 
slight  lateral  shift  of  the  patient  without  disturbing  him 
on  the  stretcher.  A  raised  ridge  projects  on  one  side  to 
engage  a  groove  in  the  stretcher  type  of  top.  This  allows 
a  certain  amount  of  longitudinal  shift.  A  little  paraffin 
as  a  -lubricant  on  the  ridge  will  serve  to  make  the  top 
move  readily,  even  with  a  heavy  patient. 


156 


U.  S.  ARIMY  X-RAY  MANUAL 


-100 


96 


Fig.  68.     Screen-carrying     mechanism,     complete     standard     army 
x-ray  table. 


NEW  APPARATUS  157 

Switch. —  (Fig.  64)  AVlien  using  the  ''Delco"  engine 
to  operate  the  portable  outfit  the  switch  may  open  and 
close  tivo  circuits ;  in  this  case  the  usual  foot  switch  camiot 
he  used.  A  special  pull  switch  (49)  operated  by  a  string 
running  along  the  rail  is  supplied. 

Screen  Support. —  (Fig.  ^^)  The  screen  support  was 
designed  to  enable  the  screen  to  be  carried  to  any  working 
position  parallel  to  the  table  top  without  having  any  por- 
tion obstructing  the  work  of  the  operator.  For  localization 
work  it  may  be  locked  in  any  desired  position. 

It  has  the  following  features : 

1.  It  runs  freely  on  the  two  side  rails. 

2.  It  is  counterbalanced  so  as  to  run  up  and  down  with 
ease. 

3.  It  may  be  rotated  about  two  vertical  axes,  enabling 
the  pierced  center  of  the  screen  to  be  brought  easily 
into  position. 

4.  It  may  be  locked  against  each  motion  separately. 

5.  It  may  be  locked  as  to  up  and  down  motion  and  yet 
rotate. 

6.  The  screen  maj^  be  inclined  if  need  arises.  The  car- 
rier is  mounted  in  a  tube  (91)  with  bearings  running 
on  the  lower  rail,  and  three  rollers  (93)  on  a  verti- 
cal axis  hold  it  in  line  on  the  upper  rail.  (96)  is  a 
heavy  tube  fitting  into  (91)  and  turns  on  a  cone 
bearing  at  the  base.  (109)  is  an  adjustable  rod  to 
which  is  attached  the  screen  clamp  (106).  (98)  is 
the  clamp  for  vertical  motion;  (95)  for  longitudinal 
run;  (94)  for  rotation  in  the  tube;  (106)  for  rota- 
tion about  the  corner  of  the  screen. 

Vertical  Insulators. —  (Fig.  62)  The  special  insulat- 
ing masts  may  be  used  as  follows : 

1.  In  base  hospital  work  wath  an  overhead  wiring  sys- 
tem they  serve  to  connect  to  the  tube  box.    They  are 


158  U.  S.  ARMY  X-RAY  MANUAL 

then  placed,  one  at  each  end  on  the  operator's  side 
of  the  table. 
2.  To  connect  the  portable  instrument  box  for  work 
with  tube  above  the  table.  They  are  then  placed 
both  at  one  end  of  the  table.  Two  extra  reels  and  a 
tube  holder  are  needed  for  this  arrangement. 
Setting  Up  Table  (Portable)— 

1.  Unpack  all  of  outfit  and  chack  list  to  ensure  that  no 
parts  are  mislaid. 

2.  Decide  on  position  for  table  and  instrument  box, 
and  which  shall  be  the  operating  side  of  table. 

3.  Lay  two  rods  (45)  down  on  side  to  be  used  by  the 
x-ray  operator;  one  of  these  must  have  locking  and 
stop  rings. 

4.  Place  end  frames  (41)  in  position  and  drop  rods  into 
notches.  Use  all  upper  notches  unless  army  litter  is 
to  be  used. 

5.  Place  screen  roller  carriage  (91)  in  position  and 
tighten  end  screws  on  all  rods.  Run  (91)  to  left 
of  operator's  position. 

6.  Hook  cradle  under  rollers  on  tube  box  with  the  two 
roller  ends  of  cradle  on  the  operator's  side  of  the 
table.  Lock  cross  brake  (51)  and  set  cradle  on  rails, 
then  release  brake  (51).  Attach  working  cross  lock 
and  be  sure  it  is  in  proper  position.     See  Fig.  65. 

7.  Attach  diaphragm  (70)  to  box  and  lock  in  position. 

8.  Set  (96)  into  (91),  then  attach  screen  and  clamp 
with  screw  (103). 

9.  Unlock  (98)  and  put  on  enough  small  weights  to 
counterbalance  the  screen. 

10.  Attach  pull  switch  to  the  end  of  table  toward  instru- 
ment box. 

11.  Pull  out  drawer  from  tube  box  and  place  on  a  good 
support. 


NEW  APPARATUS  159 

12.  Remove  cover  of  inner  box  of  tube  shipping  case  by 
unhooking  the  hasps  at  each  end,  and  raise  the  cor- 
ner by  grasping  each  hasp. 

13.  Place  the  tube  in  position  shown  in  Fig.  67.  Make 
the  cathode  connection  by  turning  the  tube  in  the 
holder  before  tightening.  Then,  approximately  cen- 
ter and  tighten  holder.  Connect  to  the  radiator  by 
means  of  a  short  piece  of  wire.  Do  not  use  screw 
as  a  binding  post. 

14.  Place  rectangular  frame  (30)  with  ridge  away  from 
operator. 

Note. — Be  sure  to  retain  the  box  intact  in  which  the 
tube  is  shipped,  and  in  case  of  reshipment  proceed  as 
follows : 

To  pack  the  tiihe,  place  it  in  the  inner  box  so  that  the 
radiator  is  14  ii^ch  from  the  end  of  the  box. 

Place  cover  of  inner  box  in  position. 

Press  cover  down  carefully  and  close  spring  hasps,  being 
absolutely  sure  that  the  hasp  is  hooked. 

After  closing  cover  of  outer  box,  fasten  down  by  means 
of  the  hasp  provided  for  that  purpose. 
Cautions — 

1.  Do  not  bend,  bruise  or  jamb  parts. 

2.  Do  not  remove  screen  without  first  locking  (98),  as 
counter  weight  may  cause  damage. 

3.  Do  not  turn  screws  so  tight  that  threads  are  stripped. 

4.  Do  not  fail  to  set  cross  run  brake  (51)  before  lifting 
tube  box  off  or  on. 

5.  If  the  supporting  side  rails  are  slightly  bent  the 
tube  carriage  will  run  hard  or  bind.  Place  box  in 
the  middle  of  the  run  and,  loosening  the  end  nuts, 
(48)  rotate  upper  rods  about  their  own  axes  until 
the  single  back  roller  is  free  on  both  sides,  i.  e.,  does 
not  rub  on  its  support. 


160  U.  S.  ARMY  X-RAY  MANUAL 

6.  Always  remove  screen  from  its  holder  before  remov- 
ing screen  carriage. 

7.  Note  the  cone  bearing  on  the  lower  end  of  the  car- 
rier post.  Do  not  stand  the  carrier  on  this,  as  it  may 
easily  be  roughened. 

8.  If  the  screen  carrier  does  not  run  freely  or  is  too 
loose  at  the  top,  the  eccentric  mounting  on  the  in- 
side of  the  roller  bearing  should  be  loosened  and  ad- 
justed so  that  there  is  very  little  play  between  these 
rollers  and  the  rail.  If  tightened  in  this  position 
the  carrier  will  run  freely. 

Also,  note  that  the  ring  (95)  has  a  hole  90°  from  the 
handle  into  which  a  small  thumb  nut  projects,  making  the 
attachment  with  the  movable  carrier;  while  (85)  has  a 
projection  intended  to  engage  a  slot  on  the  under  side  of 
the  cross  piece  of  the  cradle,  to  serve  as  a  lock  for  longitudi- 
nal run  of  tube  box. 

Some  Operating"  Points. — After  the  table  is  set  up  and 
made  reasonably  level  and  all  adjustments  have  been  made, 
it  is  strongly  advised  that  the  operator  practice  manipula- 
tion until  he  can  instinctively  and  certainly  grasp  the 
locking  devices  whenever  necessary  for  his  work. 

There  are,  then,  six  knobs  to  be  operated,  three  con- 
trolling the  screen  carrier  and  three  the  tube  box  and  dia- 
phragm. 

Number  106  will  usually  be  set  according  to  the  opera- 
tor's idea  of  using  the  screen  and  need  not  generally  be 
unlocked. 

It  is  expected  that  the  operator  will  stand  between  the 
screen  carrier  and  the  diaphragm  control,  using  the  right 
hand  to  control  the  screen  box  and  its  locks.  It  may  be 
suggested  that  if  the  operator  will  acquire  the  habit  of 
grasping  the  rod  (109)  in  order  to  control  the  screen 
position,  the  left  hand  need  never  be  in  the  radiation,  and 


NEW  APPARATUS 


161 


the  right  hand  can  remain  free  to  control  shutters  and 
rail  lock,  Fig.  69.     A  little  time  spent  in  adjusting  one's 


Fig.  69.     Method  of  handling  screen  and  shutter  on  all  standard 
army  x-ray  tables.     Litter  top  removed. 

motions  and  ideas  to  those  that  prevailed  when  the  ap- 
paratus was  designed  will  greatly  expedite  its  accurate  use. 


162 


U.  S.  ARMY  X-RAY  MANUAL 


List  of  Numbers  Referring  to  Illustrations  of  Stand- 
ard Tables 

Numbers  refer  to  the  illustrations  and  not  to  manufac- 
turers' stock  or  replacement  numbers. 


PART. 

NO. 

PART. 

NO. 

Top 

Tube  Box  Cradle 

Rectangular   frame 

30 

Stop  position  for  10  cm.  shift 

80 

Bakelite  stretcher 

31 

Rollers 

81 

Stop  for  variable  shift 

82 

Frame 

Stop  for  15  cm.  shift 
Stop 

83 
84 

End   frames 

41 

Lock  to  rail 

85 

End  frame  slots 

42 

Holes  for  mast  support 

43 

Screen  Carrier 

Rods   (side  rails) 

45 

Ring   stop 

46 

Socket  bearing 

91 

Screw   handles   on   rods 

48 

Lower    rail    carriage    frame 

92 

Switch 

49 

Upper  rail   bearing   rolls 

93 

Clamp  against  rotation 

94 

Tube  Box 

Clamp  against  longitudinal 

run 

95 

Roller  with  cross  run  lock 

51 

Main  post 

96 

Rollers  without  lock 

52 

Sliding  sleeve 

97 

Aluminum   window 

54 

Clamp   (vertical  position) 

98 

Ventilation  opening 

55 

Pulley 

99 

Register  pins   for  shutter 

56 

Wire  cord 

103 

Lock,  cross  run 

57 

Balance  weights 

101 

Partition    (lower   half) 

62 

Socket  for  horizontal  arm 

102 

Partition  (upper  half) 

63 

Clamps  (screw) 

103 

Insulator  (cathode) 

64 

Screen  holder  frame 

104 

Insulator    (anode) 

65 

Screen  holder  latch 

105 

Binding  Posts 

66 

Screen  clamp 

106 

Tube  support  posts 

67 

Knobs  to  lift  screen 

107 

Tube  clamp 

68 

Screen 

108 

Tube  centering  wire 

69 

Rod  to  screen  frame 

109 

Shutter 

Additional    High    Tension 

Insulators 

Shutter  complete              ' 

70 

Shutter  clamps 

71 

Vertical  masts 

21 

Screen  carrier  connecting  post 

72 

Frame  for  supporting  masts 

22 

Diaphragm    opening 

73 

Short   insulator   for  keeping 

Diamond-opening    control 

74 

high    tension    wires    away 

Slit-opening  control 

75 

from  frame 

23 

NEW  APPARATUS  163 

Fluoroscopic  Room  Illumination. — It  is  strongly  urged 
that  the  lighting  of  fluoroscopic  rooms  be  properly  ar- 
ranged. One  should  have  a  dim  light  for  use  in  placing 
patients,  etc.,  and  no  light  when  fluoroscoping.  The  port- 
able outfit  provides  for  operating  the  needed  light  from  the 
Delco  generator.  When  the  operating  switch  is  closed  the 
lights  go  out,  and  on  opening  this  switch  they  are  automat- 
ically lighted.  It  is  advised  that  a  ruby  lamp  be  used  in- 
tended for  operation  on  a  circuit  above  110  volts.  The 
connection  used  with  the  portable  unit  is  shown  in  Fig.  76 
and  a  similar  connection  can  be  made  for  other  outfits. 

To  Find  Target-Screen  Distance. — On  the  standard 
army  x-ray  tables  the  following  method  will  serve  to  meas- 
ure the  distance  from  target  to  screen: 

The  upright  support  TJ  fits  in  the  tube  Q,  Fig.  70  and  the 
screen  carrier  is  fastened  to  the  sliding  sleeve  B.  The  dis- 
tance from  the  top  of  the  tubing  Q  to  the  under  side  of  B 
is  related  to  the  target-screen  distance  F^S  as  shown,  Fq8 
=  n  -\-d  -\-  I  where  n  and  I  are  fixed  lengths.  Hence  if  one 
target-screen  distance  is  found,  n  -{-  I  can  at  once  be  de- 
termined. 

Put  the  cross  wire  marker  on  the  table  in  the  vertical 
ray.  Shift  the  tube  by  use  of  the  table  stops  an  exact 
distance,  say  10  or  15  cm.,  and  adjust  the  screen  up  or 
down  until  the  image  shift  and  tube  shift  are  equal.  Then 
the  target-screen  distance  is  twice  the  distance  between 
screen  and  cross  wire  marker. 

Measure  the  distance  BX  and  subtract  this  from  the 
length  so  found,  and  the  difference  is  I  +  "f^-  Record  this 
on  a  shipping  tag  and  attach  to  the  table.  Thereafter,  if 
the  target-screen  distance  is  required,  measure  BX  and  add 
I  -\-  n  as  recorded. 

To  check  your  measurement  lay  a  strip  of  metal  about 
four  inches  long  on  the  table.     Raise  the  screen  until  the 


164 


U.  S.  AR]\IY  X-RAY  MANUAL 


shadow  becomes  twice  the  length  of  the  strip.     Measure 
screen-object  distance  and  double  the  result  for  FS. 


'PTx 


^ 


^ 


rt^ 


.Q 


Screen 


7Z 


d 


Fig.  70.     Measurement  of  target-screen  distance,   standard  screen 
carrier. 


Examples — 

1.  Using  a  10  cm.  tube  shift  and  setting  the  sliders  of 
method  A  10  cm.  apart,  a  piece  of  lead  was  placed  on  the 
table  and  its  edge  so  placed  that  its  shadow  coincided  with 
one  of  the  metal  edges  of  the  marker ;  shifting  the  tube  10 
cm.,  the  screen  was  raised  until  the  shadow  of  the  lead 


NP]W  APPARATUS  165 

coincided  with  the  other  marker.  The  object-screen  distance 
was  then  38.7  cm.  The  target-screen  distance  was  then 
38.7  X  2  =:  77.4. 

2.  With  length  of  shadow  double  that  of  the  object,  the 
actual  distance  between  screen  and  the  object  w^as  39  cm. 
Double  this,  or  78  cm.,  equals  the  distance  between  the 
plane  of  the  screen  and  the  plane  of  the  focal  spot  of  the 
target. 

78  cm.  =  total  distance  screen  to  target 

45  cm.  =  variable  distance 

33  cm.  =  the  distance  that  the  sliding  or  adjustable 
piece  on  the  upright  arm  of  the  wall  meter 
is  to  be  raised  and  set  above  the  brass  lug 
on  the  lower  right. 

Centering  Tube  in  the  Box  Beneath  the  Table. — It  is 

desirable  that  the  focal  spot  of  the  target  should  be  verti- 
cally below  the  center  of  the  diaphragm  in  the  various 
methods  of  localization.  In  order  to  determine  whether  this 
is  the  case,  proceed  as  follows : 

1.  Close  up  the  diamond-shaped  opening  of  the  shutter 
to  about  1/2  inch. 

2.  Lock  the  tube  box  in  position  and  bring  the  opening 
of  the  screen  so  that  the  illumination  shows  symmetrically 
thereon. 

3.  Suspend  a  small  metal  ball,  B,  by  a  string  passing 
through  the  center  of  the  opening,  and  observe  when  this 
ball  comes  to  rest  whether  its  shadow  falls  symmetrically 
upon  the  projection  of  the  diaphragm.  If  not,  or  if  on 
narrowing  the  diaphragm  still  further,  the  narrow  beam 
of  rays  passes  by  the  ball  so  that  it  does  not  cast  a  shadow 
on  the  small  illuminated  area  of  the  screen,  it  is  evident 


166 


U.  S.  ARMY  X-RAY  MANUAL 


that  the  tube  is  not  properly  centered,  and  the  position 
of  the  shadow  also  gives  an  indication  of  the  direction  of 
tube  movement  require.     Fig.  71. 

An  approximate  idea  of  whether  the  tube  is  properly 
centered  or  not  may  be  gained  by  bringing  the  perforation 
in  the  center  of  the  screen  to  the  center  of  the  projection 
of  the  small  diagonal  opening  of  the  shutter.     When  the 


Screen 


Vlumb  Lint 1 


Screen 


Vlumb  Line 


Vertical  Tfa, 


rtical  If  ay 


Shutter 

slightly  opened 


Fo}:>^ 


Shutter 
Sliqhtlj  opened 


fife- 


Fig.  71.  (a)  Correct  position  of  shadow  of  plumb  bob.  Tube 
properly  centered. 

(b)  Projection  of  plumb  bob  on  fluorescent  screen,  incorrect  posi- 
tion. 

screen  is  down  close  to  the  table  with  the  carrier  locked 
against  longitudinal  motion  and  against  rotation,  raise  the 
screen  by  the  vertical  movement  of  the  carrier  and  see 
whether  it  retains  its  symmetrical  position.  An  idea  of  the 
amount  by  which  the  tube  needs  to  be  shifted  may  be  ob- 
tained in  this  way. 

It  is  also  suggested  that,  if  the  tube  needs  to  be  moved  in 
the  direction  in  which  the  holder  slides  out  of  the  box, 
one  can  slide  the  holder  itself  out  and  test  for  correctness, 


NEW  APPARATUS 


167 


measure  the  distance,  and  finally  shift  the  tube  the  same 
amount. 

The  U.  S.  Army  Portable  X-Ray  Unit. — By  the  coopera- 
tion of  various  manufacturers  a  semi-portable  outfit  has 
been  developed  which  may  be  used  in  mobile  units.  The 
unit  is  shown  in  Fig.  72  and  diagramatically  in  Fig.  73. 

The  important  features  of  the  outfit  are  the  portable 
power  plant,   the   self-rectifying   Coolidge   tube,   and  the 


Fig.  72.     United  States  Army  portable  x-ray  unit  complete. 


special  table.  Having  the  complete  generating  equipment, 
it  is  admirably  adapted  to  service  in  strange  territory 
where  the  electrical  supply  is  not  suitable  for  standard  ma- 
chines or  is  likely  to  fail  because  of  war  conditions. 

The  gasoline  engine  is  direct-connected  to  a  generator 
which  supplies  power  for  the  x-ray  and  filament  trans- 
formers (a.c.)  and  a  small  amount  of  current  (d.c.)  for 
the  control  circuit.  The  primary  circuit  requires  no  con- 
trol resistance,  regulation  for  the  two  working  settings 
being  made  by  shifting  the  throttle  by  means  of  the  d.-c. 


168 


U.  S.  AR]\IY  X-RAY  MANUAL 


XRflY  TUBE 


FlLFIMENT 
THRNSFORMER 


C0MI)E/\f5EH 


BLRCK 


Fig.  /3.  Wiring  diagram  for  United  States  Army  portable  x-ray 
unit.  Dotted  lines  show  connections  for  those  machines  having  spe- 
cial control.     In  other  cases  these  wires  are  omitted. 


NEW  APPARATUS  169 

control  circuit,  changing  the  speed  and  thereby  the  voltage 
of  the  generator.  The  secondary  circuit  contains  no  rec- 
tifying device  since  the  tube  allows  only  each  alternate  half 
wave  to  pass.     (See  page  36  for  a  description  of  the  tube.) 

Fluoroscopic  work  is  done  at  5  ma.  and  all  radiographic 
work  at  10  ma.  The  maximum  operating  gap  is  about  5 
inches,  but  may  be  reduced  if  desired  by  control  of  the 
machine  speed. 

Owing  to  the  drop  in  line  voltage  upon  closing  the  operat- 
ing switch,  it  is  necessary  to  secure  a  uniform  filament  cur- 
rent by  inserting  a  ''booster"  in  the  primary  circuits  of 
the  two  transformers.  This  is  merely  a  small  transformer, 
which  by  carrying  the  main  transformer  primary  current 
adds  enough  voltage  to  the  filament  transformer  primary 
to  compensate  for  the  drop  of  voltage  in  the  line. 

Engine.* — The  engine  must  be  firmly  fastened  to  a  solid 
base  by  means  of  lag  bolts  or  by  some  other  convenient 
method.  All  fuel  must  be  strained  when  filling  tank,  as 
impurities  of  any  kind  are  certain  to  clog  fuel  pipes. 

Use  a  good  grade  of  medium  oil  and  always  make  sure 
that  the  crank  case  is  well  filled  before  starting  engine. 

To  start  the  engine,  turn  the  fly-wheel  rapidly  by  means 
of  the  crank,  immediately  remove  crank  and  then  press 
starting  button  and  cut  off  air  by  means  of  lever  on  mixing 
valve  body.  When  the  engine  has  run  for  a  few  seconds, 
advance  air  adjustment  lever  to  the  point  where  the 
engine  runs  regularly  and  with  the  leanest  possible  mixture. 
A  little  practice  will  enable  the  operator  to  do  this  very 
quickly.  This  adjustment  will  vary  with  climatic  condi- 
tions and  the  kind  and  grade  of  fuel  used.  It  will  be 
found  to  be  slightly  different  when  the  engine  has  warmed 
up  from  what  it  was  when  the  engine  was  started. 

*  See  also  "Delco"  circular  on  model  9011,  furnished  by  the  manu- 
facturer. 


170  U.  S.  ARI\IY  X-RAY  MANUAL 

If  the  engine  does  not  start,  a  few  simple  tests  may 
determine  the  cause.  Go  carefully  over  all  wiring  and  be 
sure  that  all  electrical  connections  are  tight  and  clean. 
Test  to  make  sure  that  starting  battery  is  not  exhausted. 

Examine  the  spark  plug  carefully  and  if  the  porcelain  is 
broken  or  cracked,  replace  plug  with  a  new  one  if  possible. 
Hold  the  spark  plug  connecter  about  y^  inch  away  from 
spark  plug  terminal  and  turn  fly-wheel  over  several  times 
by  means  of  the  crank  and  see  if  a  good  spark  is  obtained 
in  this  manner.  If  not,  the  plug  may  be  greasy  or  dirty; 
remove  and  clean  thoroughly  with  gasoline  and  adjust 
the  distance  between  the  points  to  about  1/32  of  an  inch, 
or  until  a  dime  can  be  just  passed  between  them. 

Next,  look  at  timer  contacts  to  see  that  they  are  properly 
adjusted  and  are  making  good  contact  every  time  they  close. 
If  necessary,  clean  these  contacts  with  a  piece  of  fine  sand 
paper.  To  adjust  the  distance  between  the  points  turn  the 
engine  over  until  the  points  open  to  their  full  extent.  In 
this  position  a  dime  should  just  slip  between  the  points. 
If  necessary,  adjust  them  by  turning  the  contact  screw  in 
or  out  until  the  proper  distance  is  obtained. 

Next,  examine  commutator  and  brushes.  The  commuta- 
tor may  be  dirty  or  greasy.  It  should  never  be  allowed  to 
remain  in  this  condition,  if  the  generator  is  to  operate  at 
maximum  efficiency.  Hold  a  piece  of  clean  cloth  soaked 
in  a  little  kerosene  against  the  commutator  while  the  engine 
is  running.  Never  use  oil  other  than  kerosene  on  com- 
mutator and  always  wipe  dry  with  a  piece  of  clean  cloth 
afterwards.  Examine  brushes  to  see  that  they  are  in  good 
condition  and  are  making  good  contact. 

To  test  your  fuel  line,  fill  the  priming  cup  from  a  small 
oil  can  with  gasoline,  and  crank.  If  the  engine  will  run 
when  using  gasoline  from  the  can,  and  will  not  run  other- 


NEW  APPARATUS  171 

wise,  it  indicates  that  fuel  connections  are  loose  or  that 
the  fuel  hole  in  mixing  valve  bod}^  is  clogged.  Be  sure 
there  is  no  water  in  the  gasoline  tank.  The  fuel  hole  in 
mixing  valve  body  or  line  may  be  cleaned  out  by  blowing 
through  it  or  by  means  of  a  fine  wire.  These  few  tests 
will  usually  locate  the  trouble.  Now  look  at  the  cable  leads 
which  are  all  stamped  wdth  a  corresponding  number  on  the 
engine  switch  board.  Be  sure  that  they  are  properly  con- 
nected to  both  engine  and  transformer  unit.  The  amount 
of  gasoline  on  continuous  fluoroscopic  work  will  be  about  1 
gallon  per  hour.  On  intermittent  work,  as  is  usually  the 
actual  case,  a  gallon  w^ill  last  about  3^  hours. 

Note. — It  may  be  noted  that  the  wdring  diagram  as  in- 
dicated for  the  portable  unit  has  three  wires  to  the  voltage 
control,  and  that  the  x-ra}^  switch  has  to  open  and  close  a 
circuit,  on  the  left,  through  this  coil  and,  on  the  right, 
through  the  x-ray  transformer.  This  arrangement  w^as 
made  in  order  to  speed  up  the  engine  promptly  when  put 
under  load,  but  it  has  been  found  unnecessary^  In  some 
of  the  earlier  machines,  and  perhaps  in  the  later  ones,  this 
connection  may  be  absent.  When  this  is  the  case  the  wiring 
will  be  somewhat  simpler,  since  the  number  of  connections 
will  be  reduced  and  a  slight  change  of  design  of  the  box 
may  be  possible. 

The  Transformer  Unit. — The  x-ray  transformer  unit 
contains  the  apparatus  needed  to  transform  and  control  the 
currents  necessary  for  energizing  the  radiator  type  Coolidge 
tube  used  with  these  outfits.  It  consists  of  the  following 
parts:   (Figs.  7-1  and  75.) 

The  x-ray  transformer  (1)  transforms  the  low  tension 
alternating  current  from  the  gasoline  engine  generator 
unit  into  suitable  high  tension  current. 

The  filament  transformer  (2)  supplies  the  low  tension 
current  for  heating  the  filament  of  the  x-ray  tube. 


172 


U.  S.  ARMY  X-RAY  MANUAL 


The  booster  transformer  (3)  keeps  the  filament  of  the 
x-ray  tube  constant. 

The  filament  control   (4)   varies  the  amount  of  current 


Fig.  74.     Instrument  box  for  portable  unit,  front  view. 

passing  through  the  x-ray  tube.  A  small  knob  will  be 
found  projecting  from  the  side  of  this  regulator — this  is 
to  open  and  close  the  circuit  through  the  primary  of  the 


NEW  APPARATUS  173 

filament  transformer.  When  pushed  in  it  is  closed,  as  it 
should  ordinarily  remain. 

The  engine  rheostat  (5)  serves  as  a  means  for  controlling 
the  speed  of  the  gasoline  engine.  Moving  the  contact  to- 
ward the  front  of  the  box  increases  the  speed  of  the  engine 
and  thus  raises  the  voltage  of  the  generator. 

The  x-ray  switch  (6)  opens  or  closes  the  circuit  to  the 
primary  of  the  x-ray  transformer  and  to  the  auxiliary  throt- 
tle control. 

The  voltmeter  (7)  measures  the  voltage  of  the  generator. 

The  milliammeter  (8)  measures  the  amount  of  current 
passing  through  the  x-ray  tube. 

The  main  terminal  board  (9),  whose  five  terminals  pro- 
ject from  rear  side  of  the  case,  provides  a  means  for  con- 
necting the  x-ray  transformer  unit  to  the  gasoline  engine 
generator  unit  by  means  of  the  cable. 

The  pull  switch  terminal  board  (10)  is,  as  the  name  indi- 
cates, for  the  purpose  of  attaching  a  pull  switch  to  the 
apparatus.  The  split  lugs  at  the  end  of  the  switch  cable 
are  to  be  inserted  into  the  sockets  in  this  terminal  board 
to  connect  the  pull  switch  in  circuit.  These  connections  put 
the  pull  switch  in  parallel  with  the  x-ray  switch  and  per- 
mit the  closure  of  the  circuit  by  either  independent  of  the 
other. 

After  the  engine  and  x-ray  table  are  set  up,  place  the 
x-ray  transformer  unit  in  position,  close  to  the  end  of  the 
table  and  so  that  the  high  tension  outlets  are  equally 
spaced  between  the  legs  of  the  table.  This  is  very  im- 
portant and  should  not  be  forgotten. 

Unlock  the  box,  raise  the  lid  to  an  angle  of  about  45° 
from  horizontal,  and  slide  the  cover  of  the  box  slowly  to 
the  left  until  the  two  hinge  sections  have  been  disengaged 
one  from  the  other.  The  cover  can  now  be  removed  from 
the  box. 


174 


U.  S.  ARMY  X-RAY  MANUAL 


Pull  out  the  two  door  bolts.  The  door  in  front  can  now 
be  let  down  so  that  work  can  be  done  readily  in  the  in- 
terior of  the  box.  This  door  should  be  kept  open  at  all 
times  when  the  unit  is  in  operation  to  avoid  damage  by 
corona,  etc. 

Push  the  split  terminal  lugs  at  one  end  of  the  cable  into 


FiG.  75.     Instrument  box   for   portable  unit   showing  instruments, 
high  tension  terminals,  and  openings  for  connections. 

the  sockets  on  main  terminal  board.  These  lugs  are  of  dif- 
ferent sizes  so  that  they  will  only  fit  one  way  in  the  termi- 
nal board,  and  no  mistake  should  be  made.  Connect  the 
numbered  lugs  at  the  other  end  of  the  cable  to  the  corre- 
spondingly m'arked  connection  posts  on  the  switch  board 
of  the  engine.  Connect  pull  switch,  if  one  is  to  be  used,  by 
inserting  the  split  lugs  on  the  switch  cable  in  the  sockets 
in  the  pull  switch  terminal  board. 

The  high  tension  terminals  (11)  and  (12)  will  be  found 


NEW  APPARATUS  175 

held  in  place  in  the  cover  by  means  of  a  clamp  device. 
These  terminals  should  be  removed  and  screwed  into  the 
sockets. 

These  sockets  and  terminals-  are  provided  with  different 
sized  threads  at  their  ends  so  that  the  terminals  can  only 
fit  into  their  proper  socket.  The  high  tension  terminal  (11), 
provided  with  the  spring  hook  terminal,  screws  into  the 
single  socket.  The  remaining  terminals  (12)  can  be  screwed 
one   into   each   of  the  remaining  sockets. 

Attach  the  cord  from  the  positive  terminal  to  the  posi- 
tive terminal  of  the  tube  box  and  the  cords  from  the  two 
negative  terminals  to  the  two  binding  posts  on  the  nega- 
tive terminal  of  the  tube  box. 

Open  the  x-ray  switch,  the  pull  switch,  and  the  line 
switch  on  the  board  of  the  engine ;  move  the  sliding  con- 
tact of  the  engine-rheostat  as  close  to  the  hinge  side  of  the 
box  as  it  will  go.  Start  the  engine  and  close  the  switch 
on  the  switch  board  of  that  unit.  The  filament  of  the  tube 
should  now  be  incandescent.  Slowly  move  the  contact  on 
the  engine  rheostat  toward  the  front  of  the  box.  The 
voltmeter  should  indicate  higher  and  higher  voltage.  Con- 
tinue until  the  voltmeter  indicates  about  160  volts. 

For  radiographic  work,  having  adjusted  the  engine 
speed  by  means  of  the  engine  rheostat  until  the  voltmeter 
reads  160  volts,  set  the  filament  control  at  1.9,  close  the 
x-ray  sw^itch  and  readjust  the  engine  rheostat  and  filament 
control  until  the  milliammeter  reads  10  ma.,  when  the  volt- 
meter should  read  from  110  to  115  volts. 

Now  open  x-ray  switch  and  read  the  voltage  generated 
at  no  load,  leaving  the  rheostat  set  in  the  10  ma.  position. 
Hereafter,  whenever  radiographic  work  is  to  be  done,  sim- 
ply adjust  the  engine  rheostat  until  the  voltmeter  indicates 
the  voltage  thus  found. 

To  obtain  the  operating  point  for  fluoroscopic  work,  viz., 


176  U.  S.  ARMY  X-RAY  ]\IANUAL 

5  ma.  at  from.  110  to  115  voltmeter  reading,  reduce  the 
speed  of  the  engine  by  means  of  the  engine  rheostat 
until  the  milliammeter  indicates  5  ma.  Upon  examination 
of  the  voltmeter,  it  will  be  found  to  read  from  110  to 
115  volts.  Open  the  x-ray  switch  and  read  the  voltage  gen- 
erated at  no  load,  leaving  the  engine  rheostat  set  at  5  ma. 
point. 

Hereafter,  whenever  fluoroscopic  work  is  to  be  done,  ad- 
just the  engine  rheostat  until  the  voltmeter  again  reads  the 
voltage  thus  found. 

In  order  to  save  fuel  and  wear  and  tear  on  the  engine, 
it  may  be  advisable  to  run  the  latter  on  reduced  speed, 
except  when  making  a  radiograph,  or  during  a  fluoroscopic 
examination,  or  when  it  is  desirable  to  use  red  room  lamps 
designed  for  this  unit.  For  this  reason  an  adjustable  stop 
is  provided  on  the  engine  rheostat.  This  stop  is  set  to  bring 
the  engine  to  proper  speed  for  the  work  in  hand,  so  that 
during  the  interval  between  making  radiographs  or  fluoro- 
scopic examinations,  the  engine  speed  can  be  reduced  and 
reset  for  the  next  operation  by  merely  running  the  contact 
against  the  adjustable  stop. 

This  x-ray  transformer  unit  should,  as  far  as  possible,  be 
kept  dry  inside  and  out,  and  should  be  kept  covered  with 
a  tarpaulin  when  not  in  use.  Care  should  be  taken  to 
prevent  sudden  jarring  and  rough  handling  generally,  to 
minimize  the  danger  of  putting  meters,  etc.,  out  of  adjust- 
ment. 

The  filament  control  must  be  adjusted  carefully  to  give 
the  proper  current  and  primary  voltage,  and  once  adjusted 
it  will  stay  fixed.  Make  sure  the  filam.ent  is  lighted  be- 
fore throwing  on  power :  this  may  easily  be  forgotten  with 
an  enclosed  tube. 

Should  a  spark  pass  in  the  secondary  circuit  when  -the 
operating  switch  is  closed,  it  may  be  due  to  a  temporary 


NEW  APPARATUS 


177 


surge.  Unless  an  ''arc"  results,  do  not  open  the  operating 
switch.  Keep  secondary  wires  well  apart  and  well  away 
from  other  objects  to  prevent  corona  and  leakage.  It  is 
a  good  plan  to  connect  the  frame  of  the  table  to  any  con- 
venient ''ground." 

Red  Light  for  Fluoroscopic  Room. — The  generator  may 
readily  serve  to  give  the  reduced  red  light  needed  in  fluoro- 
scopic work.    Fig.  76  shows  how  this  is  done ;  and  either  a 


ROOM  LICiHT 


HIGH  TENSION  TO  TUBE 


TRANSFORMER 


BOOSTED 

PRiriPiRy 


Fig.  76.     Connections    for    red    lamp    over    the    fluoroscopic   table, 
when  used  with  portable  unit. 


high  voltage  ruby  lamp  or  two  16  candle  power,  110  volt 
ruby  lamps  in  series  are  required.  Do  not  connect  in  ex- 
cept as  shown  and  do  not  attempt  to  load  the  generator  up 
with  additional  lights  or  apparatus.  Pulling  the  string 
switch  alternates  x-ray  excitation  and  darkroom  illumina- 
tion. The  extension  cord  and  light  connect  onto  the  box 
at  13,  Fig.  75. 

Limitations. — This  instrument  w^ll  do  the  work  for 
which  it  is  designed,  but  must  not  be  abused.  Do  not 
use  the  radiator  type  Coolidge  tube  on  large  installations  or 
interrupterless  transformers.  It  is  not  furnished  for  this 
purpose.     It  should  only  be  used  for  radiographs  at  10 


178 


U.  S.  ARMY  X-RAY  MANUAL 


Fig.  77.  United  States  Army  bedside  unit,  complete  for  alternat- 
ing current  operation;  double  throw  switch  to  be  drawn  to  the  right, 
loose  connections  below  for  rotary  converter  in  using  direct  current. 


ma.  for  a  maximum  exposure  not  exceeding  45  sec.  with 
two  minute  intervals  between.  For  fluoroscopic  work  it 
may  be  operated  continuously,  long  enough  for  all  practi- 
cal necessities,  at  5  ma.    Do  not  attempt  to  use  this  tube  at 


NEW  APPARATUS  179 

other  than  these  settings.  Never  attempt  to  operate  the 
tube  without  the  radiator. 

The  U.  S.  Army  Bedside  X-Ray  Unit. — The  unit  shown 
in  Fig.  77  was  designed  to  permit  x-ray  examination  in 
wards  to  be  made  with  a  minimum  of  disturbance  of  the 
patient.  Many  cases  of  fracture  and  other  bone  lesions, 
as  well  as  various  chest  conditions,  need  such  examina- 
tions. Pressure  on  the  main  x-ray  outfit  is  often  reduced 
and  time  saved  by  using  such  a  unit. 

This  unit  consists  of  a  combined  cabinet  and  tube  stand, 
a  radiator  type  Coolidge  tube,  special  lead  glass  shield, 
and  a  transformer  and  control  apparatus.  The  latter  are 
enclosed  in  the  cabinet. 

Transformer. — The  transformer  (1)  is  designed  to 
operate  on  alternating  current  of  any  ordinary  frequency, 
if  properly  connected  for  the  supply  voltage  available. 
Since  the  same  primary  circuit  supplies  power  for  both 
filament  lighting  and  x-ray  operation  only  one  switch  needs 
to  be  opened  or  closed. 

Tiibe. — The  radiator  type  of  tube  (2)  with  a  special 
molded  lead  glass  shield  is  used  exclusively  on  these  units. 
The  tube  will  operate  continuously  with  5  ma.  at  a  voltage 
sufiicient  for  fluoroscopic  work. 

T  111)6  Stand. — The  tube  stand  (3)  is  counterbalanced 
and  permits  placing  the  tube  in  any  desired  position.  It 
was  made  with  a  long  horizontal  extension  to  allow  work 
over  the  top  of  a  bed.  The  position  of  the  tube  during  a 
fluoroscopic  examination  should  be  controlled  by  a  prop- 
erly trained  assistant.    See  Fig.  78. 

Limitation  of  Tube  Current. — This  outfit  was  not  de- 
signed to  permit  variation  by  the  operator  of  either  cur- 
rent or  voltage.  The  power  limit  was  fixed  by  the  usual 
fuse  capacity  of  interior  wiring  for  lighting  purposes. 
More  power  would  tend  to  blow  fuses  and  thus  interfere 


180  U.  S.  ARMY  X-RAY  MANUAL 

with  other  uses  of  these  circuits  as  well  as  delay  the  x-ray 
work.  It  gives  a  g'ood  average  result  when  two  conditions 
are  met:  (1)  a  tube  current  of  5  ma.;  (2)  a  proper  low 
tension  voltage  applied  to  the  transformer  terminals. 

Service  Conditions. — The  user  may  find  it  necessary  to 
operate  on  any  one  of  the  following  supply  systems. 


Fig.  78.     Positions    of    parts    when    using    the    bedside    unit    with 
simple  vertical  fluoroscope  for  chest  examination  at  the  bedside. 


1.  110  volt — alternating  current. 

2.  220  volt — alternating  current. 

3.  110  volt — direct  current. 

4.  220  volt — direct  current. 

Operation. — To  operate  this  unit  the  first  thing  that  it 
is  absolutely  necessary  to  know  is  whether  alternating  or 
direct  current  is  supplied  and  at  what  voltage.    Where  any 


NEW  APPARATUS  181 

question  exists  as  to  this  point,  no  attempt  should  be  made 
tc  operate  until  all  doubts  are  settled. 

This  unit  will  operate  satisfactorily  on  110  volt  alternat- 
ing current  with  no  accessories.  If  the  supply  is  110  volt 
direct  current,  a  rotary  converter  must  be  used.  Fig.  79. 
This  is  connected  by  cables  which  will  be  found  properly 
connected  to  the  switch  in  the  cabinet.     Two  leads  are  to 


Fig.  79.     Eotary  converter  used  for  direct  current  operation.   U.  S. 
Army  bedside  x-ray  unit. 

be  connected  to  the  binding  posts  on  the  rotary  marked  d.c, 
and  the  remaining  two  to  the  a.-c.  terminals  of  the  rotary. 
No  mistake  should  be  made,  as  these  cables  are  plainly 
marked.  On  220  volt,  direct  current,  this  unit  may  still 
be  used,  but  a  220  volt  rotary  will  be  required.  The  rotary 
converter  for  220  volts  is  mounted  on  a  wooden  base  and 
has  a  suitable  series  resistance.  This  rotary  is  designed 
and  adjusted  to  give  110  volts  a.c.  at  the  collector  rings 
under  load. 


^4=^ 


TJ^ftNSFORMEn 


M       ,r     ^x 


^ 


r(9  LINE 


FU6E 


'^  r 


3= 


,^^"7^ 


^ 


70  OFBRRTING 
SWITCH 


TO  FOOT  ew/TCH 


TiOWFY  CON\/BRTOR 

Fig.  80.     Wiring    diagram    for    connections,    United   States   Army 
bedside  unit  for  110-220  volt,  d.c.  or  110  volt  a.c. 

182 


NEW  APPARATUS 


183 


X-Ray  Transformer. — The  x-ray  transformer  has  three 
bmding  posts  numbered  1,  2,  and  3.  One  and  three  are 
used  in  all  cases  except  for  110  volt  direct-current  opera- 


i^UTO  JBRNSFORMEFi 


■ftC 


DC' 


n     □ 


r~c 


h- 


Z20  VOLTS    ftC 


L 


TO  mrmy 


TO   OPEnflTlNG 
SWITCH 


TO  FOOT  SWITCH 


Fig.  81.     Wiring  diagram  for  connections,  United  States  Army  bed- 
side unit  for  220  volts  a.-c.  circuit. 


tion,  for  which  numbers  1  and  2  are  used.  When  the  wire 
is  removed  from  part  three  it  should  be  taped  so  as  not  to 
make  an  accidental  contact.  Fig.  80  shows  in  full  lines 
the  connection  for  110  volt  d.c,  220  d.c.  and  110  a.c.  The 
switch  must  be  closed  on  d.c.  for  both  direct-current  volt- 


184  U.  S.  ARMY  X-RAY  MANUAL 

ages,  and  on  the  a.c.  side  for  both  voltages  of  alternating 
current. 

If  the  current  is  220  alternating  a  special  autotransformer 
is  required.  The  one  that  is  supplied  has  three  wires 
marked  1,  2,  and  3.  To  connect  up  for  this  voltage  (Fig, 
81)  transfer  the  line  wires  to  terminals  1  and  3  of  the  auto- 
transformer and  connect  1  of  the  x-ray  transformer  to  2 
of  the  autotransformer  and  3  of  the  x-ray  transformer  to  3 
of   autotransformer. 

Tube. — The  radiator  type  Coolidge  tube  will  be  used 
exclusively  on  these  outfits  and  little  or  no  adjustment  can 
or  will  be  left  to  the  operator.  This  tube  does  not  require 
a  rectifier  of  any  description  and  will  safely  carry  5  ma, 
for  an  indefinite  time.  For  radiographic  work  it  is  advis- 
able to  use  intensifying  screens. 

To  Adjust  the  Tube — 

1.  Remove  radiator  after  loosening  screw  at  the  end. 

2.  Carefully  place  the  two  halves  of  the  lead  glass 
shield  (4)  over  the  tube  and  fasten  together  by  means  of 
the  screws.  Do  not  turn  screws  tight  or  a  broken  shield  is 
sure  to  result. 

3.  Turn  the  tube  so  that  the  center  of  the  target  is  in 
line  with  the  opening  in  the  shield  (5). 

4.  Push  the  cork  wedges,  which  are  supplied,  in  around 
the  target  end  of  tube  first,  then  in  around  cathode  end 
so  as  to  hold  tube  firmly  in  this  position.  Replace  radia- 
tor. If  this  screw  does  not  turn  easily,  hold  the  tube  by 
the  radiator  and  not  by  the  glass.  Never  attempt  to  operate 
this  tube  without  the  radiator  in  place. 

"When  placing  the  tube  in  the  holder  be  sure  that  the 
shield  containing  the  tube  is  clamped  in  the  holder  (6)  and 
not  the  tube  ends.  To  adjust  the  aluminum  filter,  which  it 
is  necessary  to  use  at  all  times,  loosen  the  two  screws  that 
hold  the  shield  together  each  side  of  the  opening,  place  the 


NEW  APPARATUS  185 

aluminum  filter  in  position  and  retighten  screws,  always  re- 
membering tliat  glass  will  break  if  fastened  too  tight.  The 
diaphragm  with  the  round  hole  will  cover  an  area  5  inches 
in  diameter  at  20  inches  target-screen  distance,  and  the 
square  opening  an  area  14:  inches  square  at  the  same  tar- 
get-screen distance.  A  strip  of  lead  foil  may  be  attached 
by  adhesive  tape  over  the  crack  between  the  two  halves  of 
the  lead  glass  shield. 

After  everything  else  is  ready  connect  with  your  source 
of  current  and  make  sure  that  you  throw  the  two-way  switch 
to  the  correct  side.  Both  ends  are  marked  and  there  can  be 
no  excuse  for  not  doing  this  right.  After  throwing  this 
switch,  watch  the  milliammeter.  If  it  goes  to  more  than  5 
ma.,  adjust  the  resistance  wire  on  the  top  of  the  terminal 
inside  the  cabinet,  increasing  the  amount  included  between 
binding  posts;  if  less  than  5  ma.,  reduce  the  amount  so 
included  until  the  milliammeter  reads  between  4i^  and 
5  ma. 

This  apparatus,  operated  as  directed,  will  do  the  work 
for  which  it  was  designed.  The  operator  should  not  at- 
tempt any  adjustments  other  than  those  described.  All 
others  have  been  attended  to  by  the  designers  and  makers. 
It  is  intended  that  intensifying  screens  should  be  used 
with  this  unit  for  all  radiographic  work,  unless  immobili- 
zation is  easily  accomplished. 

Care  in  Moving. — The  tube  holder  permits  of  placing 
the  tube  as  shown  in  Fig.  77,  so  that  when  moving  in  a 
ward  there  is  less  danger  of  collision  between  the  tube  and 
other  objects.  Always  move  carefully  as  the  tube  is  frag- 
ile. "When  the  holder  is  extended  the  cabinet  is  less  stable, 
and  even  more  care  must  be  taken.  AYhen  moving  up  or 
down  stairs  always  remove  the  tube  and  clamp. 

Exposure. — The  exposure  recpiired  with  this  outfit  will 
depend  on  conditions  as  to  film  or  plate,  and  on  whether 


186  V.  S.  ARMY  X-RAY  MANUAL 

an  intensifying-  screen  is  used  and  its  speed.  If  one  is 
accustomed  to  using  40  ma.  at  about  a  5-inch  gap,  with  the 
same  conditions  as  to  distance  and  plate  or  film,  the  time 
of  exposure  is  to  be  multiplied  by  eight.  Using  an  inten- 
sifying screen  will  reduce  this  exposure  an  amount  depend- 
ing on  the  multiplying  power  of  the  screen  used.  A  good 
screen  will  reduce  the,  exposure  time  to  from  1/10  to  1/15 
of  that  required  with  no  screen,  when  a  plate  or  a  single- 
coated  film  is  used. 

If  a  double-coated  film  is  supplied,  the  time  without 
screens  is  reduced  to  %.  For  double-coated  film  and 
single  screen,  the  time  is  further  reduced,  under  good  con- 
ditions, to  about  1/25  or  1/30  of  that  for  single  coating 
and  no  screen. 

An  excellent  chest  negative  of  a  man  of  average  size 
has  been  made  with  the  following  settings: 

Target-plate  distance — 28  inches. 

Current — 5  ma. 

Eastman  double-coated  film. 

Edwards  screen  (single). 

Exposure  time — 1  sec. 

A  little  care  and  practice  will  enable  one  to  do  a  large 
amount  of  work  at  a  minimum  of  disturbance  or  discom- 
fort to  the  patient  and  with  quite  reasonable  exposure 
times. 

Accessory  Apparatus. — Hand  fluoroscope  5x7,  the 
usual  type  for  examination  of  extremities. 

Fluoroscope  for  chest  examination  with  special  support. 
See  Fig.  78.  This  can  be  folded  and  disassembled  for  mov- 
ing from  place  to  place. 

Reducing  goggles  are  furnished  to  enable  the  operator  to 
find  his  way  around  a  lighted  room  and  then  proceed  at 
once  to  do  reasonably  good  fluoroscopic  work.  These  con- 
tain a  red  and  a  green  celluloid  disc;  for  a  fairly  dark 


NEW  APPARATUS  187 

room  the  red  alone  may  serve,  for  a  brightly  lighted  room 
both  are  inserted.  Just  before  bringing  the  fluoroscope 
in  position,  close  the  eyes,  raise  the  goggles  to  rest  on 
the  forehead,  and  open  the  eyes  only  after  the  fluoroscope 
is  in  position.  Reverse  these  steps  when  the  examination 
is  completed. 

Fluoroscopic  Unit. — ^For  the  most  successful  and  con- 
venient fluoroscopy  the  operator  should  have  control  over 
both  screen  brightness  and  the  penetration  of  the  rays.  A 
unit  embodying  these  control  features  and  of  correct  ca- 
pacity for  operation  with  the  self -rectifying  Coolidge  tube 
has  been  devised  and  is  in  limited  use  in  connection  with 
the  horizontal  and  vertical  fluoroscope,  although  not  offi- 
cially adopted  and  regularly  supplied  by  the  government. 
The  transformer  is  about  the  same  size  as  that  used  in  the 
bedside  unit  but  differs  in  having  entirely  separate  high 
tension  and  filament  transformers  in  the  same  case,  rather 
than  two  secondary  windings  energized  by  the  same  pri- 
mary as  has  the  bedside  unit.  The  primary  of  the  high  ten- 
sion transformer  and  the  primary  of  the  Coolidge  filament 
transformer  may  be  separately  controlled  by  turning  two 
knobs  on  the  control  cabinet,  giving  various  tube  currents 
and  voltages  with  a  much  simpler  adjustment  than  here- 
tofore in  use. 

This  unit  serves,  in  those  instances  where  it  is  installed, 
to  remove  the  fluoroscopic  work  from  the  large  standard 
machine  and  thereby  increase  the  capacity  of  the  x-ray 
room  without  the  addition  of  another  high  power  outfit. 
It  can  be  run  from  110  volts  a.c,  from  220  volts  a.c. 
by  means  of  a  small  autotransformer,  or  from  110  or 
220  volts  d.c.  with  a  suitable  rotary  converter.  A  wiring 
diagram  is  supplied  with  the  machine. 


STANDARD    POSITIONS 

It  has  been  the  endeavor,  in  the  following  series  of  pho- 
tographic reproductions  of  the  various  parts  of  the  body, 
to  illustrate  what  seem  the  simplest  and  most  reliable 
methods  of  securing  x-ray  plates  of  these  various  parts, 
which  are  of  most  value  in  determining  both  the  normal 
and  the  pathological  structure. 


Fig.  82.    Position:    (a)  clavicle  (b)   shoulder  joint. 


The  necessity  for  a  thorough  knowledge  of  normal  x-ray 
shadows  is  too  apparent  to  need  further  discussion  here. 
No  amount  of  study  and  observation  of  pathological  or 
abnormal  conditions  will  be  of  value  unless  the  individual 
has  first  acquired  a  true  concept  of  the  normal.    In  order 

188 


Fig.  83.     Elbow,  lateral  view. 


Fig.  84,     Elbow,    anteroposte- 
rior view. 


Fig.  85.     Wrist,      anteroposte-  FiG.  86.     Wrist,  lateral  view, 

rior  view. 

189 


190 


U.  S.  ARMY  X-RAY  MANUAL 


to  obtain  such  a  concept  some  method  must  be  followed 
which  will  give  the  least  amount  of  variation  in  the  ap- 
parent size,  shape,  and  relation  of  the  parts  examined 
when  attempting  to  reproduce  the  same  results  in  the 
same  or  different  patients.     This  is  essentially  the  funda- 


FlG.  87.     Hip  joint,  anteroposterior  view. 

mental  principle  of  all  x-ray  interpretation.  It  has  been 
found  by  roentgenologists  that  this  can  only  be  accom- 
plished by  establishing  standard  relations  between  the 
source  of  the  rays,  the  sensitive  plate  and  the  part  to  be 
examined.  This  is  what  is  meant  when  speaking  of  the 
standard  positions  for  the  different  parts  of  the  body.  It 
must  be  constantly  borne  in  mind  that  even  a  slight  change 


STANDARD  POSITIONS 


191 


m 


Fig.  88.     Knee,  antero-  FiG.  89.     Knee,  lateral  view, 

posterior  view. 


Fig.  90.     Ankle,  antero- 
posterior view. 


Fig.  91.     Ankle,  lateral  view   (mark- 
er   over    internal    malleolus). 


192 


U.  S.  ARMY  X-RAY  MANUAL 


Fig.  92.  F  o  o  t,  anteroposterior 
view. 

Fig.  93.  Foot,  lateral  view,  mark- 
er over  first  metatarsal. 


Fig.  92 


Fig.  94.     Position  for  demonstration  of  the  posterior  portion 
of  OS  calcis;  arrow  indicates  the  direction  of  the  rays. 


STANDARD  POSITIONS  193 

in  the  relative  positions  of  the  targ-et,  plate,  and  part 
may  result  in  some  distortion  which  might  render  the 
plate  of  doubtful  value  in  any  endeavor  to  determine  the 
abnormal  by  its  comparison  with  the  normal.  While  ex- 
perience has  shown  that  the  best  results  are  obtained  by 
adhering  to  these  positions,  it  must  be  remembered  that 
often  they  must  be  modified  to  meet  the  need  of  individual 
cases. 

Several  illustrations  of  standard  positions  which  are 
not  shown  elsewhere  in  the  manual  are  here  grouped  to- 
gether. 

These  are  the  only  parts  of  the  bod}^  which  the  x-ray 
manipulator  should  be  allowed  to  examine.  All  other  ex- 
aminations require  the  personal  attention  of  the  roent- 
genologist. 


DANGERS    AND    PROTECTION 

Dangers  from  the  X-Rays. — The  danger  to  the  skin  of 
operator  and.  patient  requires  careful  consideration  in 
order  to  avoid  serious  injury.  It  is  customary  to  speak  of 
a  dose  that  will  cause  a  slight  temporary  redness  of  the 
skin  as  an  erythema  dose.  This  dose  undoubtedly  varies 
considerably  according  to  the  age  of  the  patient  and  to 
the  judgment  of  the  observer  as  to  the  extent  of  redness 
U^hich  may  be  called  ''slight." 

The  skin  dose  will  depend  on  the  following  factors : 

1.     Target-skin  distance. 
Spark  gap   (voltage). 
Current  through  the  tube. 
Time  or  duration  of  exposure. 
Nature_and  thickness  of  filter  used. 

While  complete  agreement  as  to  what  will  give  an  ery- 
thema dose  can  hardly  be  expected,  all  will  agree  that  the 
dose  will  increase  with  the  duration  of  exposure,  with  the 
current  and  with  the  spark  gap ;  and  will  decrease  as  dis- 
tance between  target  and  skin  is  increased  and  as  thicker 
filters  are  used. 

It  is  convenient  in  this  connection  to  combine  the  tube 
current  in  ma.  and  the  time  in  minutes,  and  speak  of 
milliampere  minutes,  but  it  must  he  clearly  understood 
that  the  nuniber  of  milliampere  minutes  allowable  varies 
with  the  spark  gap. 

Working  at  a  target-skin  distance  of  20  inches  and  a 
5-inch  gap,  45  milliampere  minutes  may  be  safely  allowed 


DANGERS  AND  PROTECTION  195 

if  no  filter  is  "used.    For  general  saf  ety^a  filter  of  1  mm.  -f  *'*'^*  ^ 
of  aluminum  is  advised,  and  the^_an_inerease_of  about  40  ^  ^^^ 

£er  cent  may  be  allowed — or  about  60  ma.  minutes  may 
be  taken  as  a  safe  total  to  be  received  by  the  skin  at 
this  gap  and  target-skin  distance.  Thus,  at  5  ma. — 5-inch 
gap — 20  inches — 1  mm.  al.,  a  total  of  twelve  minutes  may 
be  used  on  one  skin  area  for  fluoroscopic  examination,  if 
no  radiograph  is  to  he  taken. 

If  20  ma.  minutes  at  a  5-inch  gap  were  used  in  fluoro- 
scopy there  remains  only  40  ma.  minutes  for  radiographic 
work.  If  40  ma.  is  used  and  10  seconds  is  required  for  a 
negative,  only  6  plates  could  be  safely  made.  On  this 
account  it  is  wise  to  make  fluoroscopic  examinations  as 
brief  as  is  consistent  with  good  work  and  to  use  intensify- 
ing screens  in  serial  radiography. 

A  very  important  point  to  remember  is  that  when  using 

a  smaller  gap,  although  the  amount  of  radiation  reaching 

the  skin  is  less  for  the  same  current,  the  exposure  required 

in  radiographic  work  is  very  much  longer.     To  get  the 

"same  plate  density  at  lower  gaps,  the  skin  risk  is  greater. 


Many   cases   of   dermatitis   are   due   to   prolonged   or   re- 


peateHexposure  with  too  small  a  back-up  gap  for  the  work 
in  hand. 


Be  sure  that  unfiltered  rays  along  the  axis  of  the  tube, 
which  do  not  TTaveto  pass  through  the  lead  glass  bowl,  do 
not^each  the  patient. 

When  an  erythema  dose  is  reached  orapproached^_an 
interval  of  three  weeks  should  elapse  before  again  expos- 
ing! 

Exposure  beyond  an  erythema  dose  may  be  justified 
when  circumstances  arise  of  an  unusual  nature.  But  the 
surgeon  or  attending  physician  should  be  warned  by  the 
roentgenologist  before  such  a  risk  is  to  be  taken. 

Protection  of  the  Operator  from  the  X-Rays. — The  ele- 


196  U.  S.  AR:\IY  X-RAY  IMANUAL 

ment  of  increase  in  the  work  time  makes  care  in  the  protec- 
tion of  the  operator  of  extreme  importance.  Two  things 
are  clear  in  this  matter :  First,  that  effects  are  cumulative ; 
second,  that  evidence  of  injury  may  develop  late.  Since  the 
demands  of  the  art  fix  the  amount  of  radiation  for  specific 
purposes,  the  operator  can  do  only  three  things  for  self- 
protection. 

1.  Increase  the  distance  from  the  target  to  any  part 
of  his  body. 

2.  Interpose  absorbing  material  between  himself  and 
the  tube. 

3.  Reduce  the  time  devoted  to  the  work. 

The  first  of  these  is  applicable  in  radiographic  work 
only,  as  in  fluoroscopy  he  must  work  at  close  range.  The 
third  can  have  only  limited  application  in  a  military  hos- 
pital during  war,  so  the  second  is  the  practical  method. 

The  following  suggestions  are  offered  in  the  hope  that 
they  may  be  applied : 

1.  That  in  all  Radiographic  and  treatment  work  no 
direct  rays  be  allowed  to  reach  the  operator's  body  without 
passing  through  at  least  1/16  inch  of  lead  where  lead  can 
be  used.  Lead__^ass  should  have  an  absorption  equivalent 
to  1/32  inch  of  lead.  ^ 

2.  That  in  addition  to  this  lead  protection,  the  opera- 
tor keep  several  feet  from  the  tube  in  treatment  and  heavy 
radiography. 

3.  That  in  using  either  a  vertical  or  a  horizontal  flu- 
oroscope,  a  careful  test  be  made  to  ensure  that  no  direct 
rays  come  through  bad  joints,  holes  in  lead,  or  other  un- 
protected openings. 

4.  That  the  fluoroscopic  screen  be  protected  with  lead 
glass  at  least  equivalent  to  1/32  inch  of  lead. 

5.  That  the  lead  glass  and  sheet  lead  on  the  frame  over- 
lap at  least  %  inch. 


DANGERS  AND  PROTECTION       197 

6.  That  the  diaphragm  never  be  opened  or  moved  so 
as  to  send  part  of  the  beam  past  the  screen,  and  1  nun.  of 
aluminum  be  used  as  a  filter  in  all  cases. 

7.  That  in  horizontal  fluoroscopy  some  protection  be 
given  for  rays  scattered  at  right  angles  to  the  patient's 
body. 

8.  That  the  operator  study  his  working  conditions  so 
as  to  secure  the  results  required  in  the  minimum  time. 

Under  no  circumstances  should  an  operator  use  any  part 
of  his  body  for  fluoroscopic  demonstration,  nor  should  he 
hold  any  plate  or  dental  film  in  position  during  exposure. 

It  should  be  understood  that  the  final  responsibility  for 
protection,  both  of  the  patient  and  the  operator,  rests  on 
the  roentgenologist  himself,  and  after  his  apparatus  is 
installed  he  should  not  neglect  to  test  for  gross  leaks  and 
insufficient  protection. 

The  fluoroscopic  screen  in  a  well-darkened  room  will 
help  to  find  where  danger  may  lurk  but  gives  no  idea  of 
the  amount  of  radiation  involved  in  the  indicated  direc- 
tions. 

According  to  the  work  of  Pfahler  and  others,  on  a  5-inch 
gap  the  number  of  milliampere-minutes  required  with  un- 
filtered  radiation  for  a  full  erythema  dose  at  20  inches, 
allowing  no  factor  of  safety,  will  be  about  60.  This  means 
that  without  filter,  5  ma.,  at  a  5-inch  gap,  20  inches  tar- 
get-skin distance,  12  minutes  will  almost  certainly  give 
a  skin  inflammation. 

A  test  of  the  danger  may  be  made  as  follows :  take  a  few 
dental  films,  number  them,  and  place  in  the  position  occu- 
pied by  the  operator's  body  when  at  work,  but  attached 
to  his  clothing.  After  he  has  worked  for  some  time,  de- 
velop these  films  and  note  their  general  density. 

Then  using  the  above  data,  5  ma.  at  20-inch  target-plate 
distance  and  a  5-inch  gap,  expose  a  series  of  films  for  defi- 


198  U.  S.  ARMY  X-RAY  ]\IANUAL 

nite  fractions  of  the  time  required  for  an  erythema  dose. 
These  fractions  must  be  small  and  care  must  be  taken  to 
develop  these  films  exactly  as  the  test  films  were  devel- 
oped. In  this  way  it  is  possible  to  determine  the  time  the 
operator  must  work  to  approximate  an  erythema  dose. 
Probably  %  such  a  dose  per  month  would  not  have  any 
serious  effect. 

Electrical  Dangers. — In  the  use  of  high-power  x-ray  ap- 
paratus, care  must  be  taken  to  avoid  discharge  from  high 
tension  lines  to  earth  through  the  body  of  either  patient 
or  operator.  Fatal  results  may  follow,  and  in  any  event 
the  nervous  shock  to  the  patient  may  be  serious.  Danger 
arises  from  sparks  followed  by  an  arc  discharge  from  the 
high  voltage  line  to  the  body,  thence  to  earth. 

To  get  such  a  discharge,  we  must  have : 

1.  Grounding  of  patient  or  contact  with  badly  insu- 
lated grounding  material. 

2.  So  short  an  air  distance  from  some  part  of  the  high 
tension  system  as  will  allow  a  break  over  spark. 

A  single  spark,  while  disconcerting,  is  not  dangerous 
to  life,  but  it  serves  to  pave  the  way  for  a  heavy  discharge 
from  the  line  if  the  supply  is  maintained.  On  static  ma- 
chines and  most  induction  coils,  body  connection  so  re- 
duces the  line  voltage  as  to  preclude  any  fatal  amount  of 
current ;  but  with  the  modern  high  power  transformer  it  is 
a  difif^erent  matter. 

The  danger  of  an  initial  spark-over  to  the  body  is 
solely  a  matter  of  line  to  skin  distance  and  voltage  from 
line  to  earth.  When  a  tube  is  taking  current,  the  voltage 
from  either  line  to  earth  is  less  than  it  would  be  on  the 
same  control  setting  if  no  current  were  passing.  Hence, 
failure  of  the  tube  to  take  current  at  any  time  tends  to 
cause  discharge  to  the  patient.  The  following  are  the  com- 
mon ways  in  which  this  may  happen : 


DANGERS  AND  PROTECTION       199 

1.  Failure  to  complete  high  tension  connection. 

2.  ''Cranky"  gas-tube. 

3.  Failure  to  light  Coolidge  filament  before  turning  on 
high  tension. 

4.  Break  or  disconnection  of  Coolidge  filament  circuit 
while  running. 

5.  Attempting  to  pass  current  through  Coolidge  tube 
in  wrong  direction. 

Another  cause  for  spark-over  is  the  high  tension  surge 
often  caused  on  closing  the  primary  switch  of  the  trans- 
former. 

Keep  all  high  tension  lines  at  least  twice  as  far  from 
any  portion  of  the  patient  as  the  working  spark  gap. 
Thus,  if  using  an  equivalent  gap  of  6  inches,  allow  no 
wire  closer  than  12  inches.  A  grounded  metal  or  con- 
ducting screen  heticeen  the  high  tension  lines  and  the  pa- 
tient is  complete  protection  for  the  patient ;  thus,  a  hori- 
zontal fiuoroscope  with  a  grounded  frame  is  safe  with 
the  tube  below;  but  when  the  patient  is  between  the  high 
tension  line  and  a  grounded  metal  or  conducting  table, 
danger  is  greatly  increased. 

Type  of  Control. — Much  has  been  said  of  the  relative 
danger  with  various  controls.  Simply  stated  it  amounts 
to  this :  the  rise  in  voltage  when  the  tube  fails  to  take 
current  is  very  much  greater  on  a  resistance  control  (See 
Figs.  19  and  20),  so  that  the  chance  of  an  initial  spark 
is  greater;  but  after  such  a  spark,  the  chance  of  a  fol- 
lowing arc  is  reduced  by  reason  of  resistance  in  the  pri- 
mary circuit. 

With  autotransformer  control,  or  operation  without  re- 
sistance— i.  e.,  with  rheostat  all  out — the  rise  in  voltage 
on  open  circuit  is  less;  but  if  an  arc  is  started,  it  is  very 
dangerous.  A  quick-acting,  over-load  primary  break  is 
very  desirable. 


200  U.  S.  ARMY  X-RAY  MANUAL 

Resuscitation  from  Electric  Shock  or  Asphyxiation. — 

The  prone  pressure  method  of  artificial  respiration,  de- 
vised by  Prof.  Schaefer,  of  Edinburgh,  has  been  advocated 
as  the  most  effective  method  by  the  United  States  Bureau 
of  Mines'  Committee.  This  method  can  be  used  with 
oxygen  inhalator.  It  should  always  be  used  immediately 
to  resuscitate  asphyxiated  persons  and  kept  up  continu- 
ously until  approved  mechanical  resuscitating  devices  are 


Fig.   95.     Eesuscitation  from  electric   shock. 
Above — Expiration,    pressure    on.     Below — Inspiration,   pressure   off. 

brought  to  the  scene  and  adjusted  on  the  patient.  Heart 
stimulant  should  be  given  as  frequently  as  necessary. 

This  system  can  be  used  in  cases  of  electric  shock,  after 
the  victim  has  been  removed  from  the  live  conductor,  in 
cases  of  gas  poisoning  or  asphyxiation  from  any  cause. 
Artificial  respiration  should  he  hegun  promptly,  as  life 
persists  only  a  few  minutes  after  hreatliing  stops. 

Quickly  feel  with  your  finger  in  the  victim's  mouth 
and  throat  and  remove  any  foreign  body  (tobacco,  false 
teeth,  etc.),  then  begin  artificial  respiration  at  once.  Do 
not  stop  to  loosen  patient's  clothing;  every  moment  is 
precious. 


DANGERS  AND  PROTECTION  201 

Lay  the  subject  on  his  belly,  with  arms  extended  as 
straight  forward  as  possible,  and  with  face  to  one  side, 
so  that  the  nose  and  mouth  are  free  for  breathing.  Draw 
forward  the  subject's  tongue. 

Do  not  permit  bystanders  to  crowd  around  and  shut 
off  the  air. 

Kneel,  straddling  the  subject's  thighs  and  facing  his 
head;  rest  the  palms  of  your  hands  on  the  loins  wdth 
thumbs  nearly  touching  and  with  fingers  spread  over  the 
lower  ribs.    Fig.  95. 

With  arms  held  straight,  swing  forw^ard  slowly,  so  that 
the  weight  of  your  body  is  gradually  brought  to  bear 
upon  the  subject.  This  operation,  which  should  take  two 
or  three  seconds,  must  not  be  violent,  lest  internal  organs 
be  injured.     The  air  is  thus  forced  out  of  the  lungs. 

Now  immediately  swing  backward  so  as  to  remove  the 
pressure,  but  leave  your  hands  in  place.  The  air  thus 
enters  the  lungs. 

After  two  seconds  swing  forward  ag'ain,  repeating  this 
operation  twelve  to  fifteen  times  to  a  minute,  a  complete 
respiration  every  four  or  five  seconds.  While  this  is  be- 
ing done,  an  assistant  should  loosen  any  tight  clothing 
about  subject's  neck,  chest  or  waist. 

Continue  artificial  respiration  (if  necessary)  two  hours 
or  longer,  without  interruption,  until  natural  breathing 
is  restored.  Even  when  natural  breathing  begins,  care- 
fully watch  that  it  continues.  If  it  stops,  begin  artificial 
respiration  again. 

Keep  subject  warm  by  applying  a  proper  covering  or 
artificial  heat,  hot  water  bags,  etc. 

Do  not  give  stimulants  or  liquids  by  mouth  until  sub- 
ject is  fully  conscious. 


FLUOROSCOPY 

Definition. — Fluoroscopy  is  the  method  of  making 
studies  of  opaque  objects  by  means  of  the  x-rays  and  the 
fluorescent  screen.  It  depends  upon  the  fact  that  under 
the  influence  of  the  x-rays  certain  substances  become 
highly  fluorescent.  The  fluorescent  screen  consists  primar- 
ily of  a  thin  layer  of  this  fluorescent  substance  spread 
upon  cardboard.  This  cardboard  or  fluorescent  screen  in 
turn  should  be  covered,  by  lead  glass  having  an  absorbing 
capacity  equivalent  to  1/32  inch  of  lead,  and  mounted  in 
a  frame.  To  this  frame  there  should  be  attached  con- 
venient handles,  and  these  handles  should  be  so  arranged 
that  the  hands  will  be  protected  from  stray  raj^s  during 
the  examination.  "When  not  working  in  a  well-darkened 
room  the  screen  must  be  covered  by  a  hood  so  as  to  shut 
out  other  light.  This  hood  is  usually  arranged  in  a 
pyramidal  form.  The  depth  of  this  pyramid  must  be  at 
least  the  average  focal  distance  for  the  eyes. 

A  fluoroscope  for  use  in  a  lighted  room  has  been  de- 
scribed by  Dr.  Dessane  (Gallot  et  Cie),^  Figs.  96  and  97. 
A  spring  attached  across  the  hinge  line  will  hold  the  fluoro- 
scope down  in  its  working  position,  or  when  tilted  over  it 
will  be  held  by  the  same  spring  in  position  on  top  of  the 
head. 

Apparatus. — If  the  apparatus  is  to  be  used  solely  for 
fluoroscopic  work  the  exciting  outfit  needs  to  be  capable 

^Described  by  L.  Ombredanne  et  E.  Ledoux-Lebard,  ''Localization 
et  Extraction  des  Projectiles,"  Libraries  de  L'Academie  de  Medi- 
cine, Paris. 

202 


FLUOROSCOPY  203 

of  producing  no  more  than  5  to  10  milliamperes  with  a 
voltage  corresponding  to  from  3-ineh  to  6-inch  parallel 
spark  gap.  A  coil  run  by  a  mechanical  interrupter  will 
give  very  satisfactory  x-ray  light  for  fluoroscopic  work. 

The  great  bulk  of  fluoroscopic  work  in  military  hospitals 
will  be  done  in  the  horizontal  position.  It  will  be  the  po- 
sition most  desirable  for  the  localization  of  foreign  bodies, 


Fig.  96.     Dessane's  fluoroscope  attached  to  the  liead  ready  for  ex- 
amination. 


the  study  and  manipulation  of  fractures  and  of  the  stom- 
ach and  intestines. 

An  outfit  for  vertical  fluoroscopy  is  also  desirable  in 
military  work.  Its  greatest  use  will  be  in  the  study  of 
cavities  containing  fluid,  such  as  cavities  in  the  lungs,  ac- 
cumulations of  fluid  in  the  pleura  or  the  study  of  opaque 
fluids  placed  in  the  stomach  and  intestines  to  render  them 
opaque  and  visible.  In  this  vertical  position  one  can  often 
obtain  the  upper  level  of  fluid  and  make  an  absolute  diag- 
nosis of  a  condition  that,  when  studied  in  the  horizontal 
position,  would  give  less  evidence  leading  to  a  correct 
diao^nosis. 


204  U.  S.  ARMY  X-RAY  MANUAL 

Operating"  Switch. — This  switch  should  be  adjusted: 
(1)  so  that  the  operator  need  not  continuously  stand  on 
one  leg;  (2)  so  that  it  will  accurately  and  quickly  close  or 
open  the  primary  circuit;  (3)  and  so  that  it  will  turn  on 
and  off  the  ruby  light  which  is  used  for  general  lighting 
of  the  fluoroscopic  room.     (See  page  177.) 

The  Darkroom,  Importance  of  Absolute  Darkness. — Too 


Fig.  97.  Dessane's  fluoroscope  elevated  to  the  top  of  the  head 
after  the  fliioroscopic  examination  has  been  made  permitting 
the  operator  to  see  by  ordinary  light  without  losing  the  sensibility 
of  the  retina  because  of  a  ruby  glass  which  automatically  drops  in 
front  of  the  eyes  as  the  fluoroscope  is  elevated. 

much  emphasis  cannot  be  laid  upon  the  necessity  of  ab- 
solute darkness,  especially  if  an  open  screen  is  to  be 
used.  The  success  in  attaining  absolute  darkness  will  de- 
pend in  great  part  upon  the  ingenuity  of  the  operator. 
Black  cloth  or  black  paper  is  a  cheap  way  of  rendering 
cracks  and  light  fissures  dark.  To  cover  windows  and 
other  openings,  double  black  curtains  running  in  grooves 
will  be  found  the  most  satisfactory.  Unless  the  room  be 
absolutely  dark  the  object  under  study  will  be  dim  in  out- 
line and  in  many  instances  not  even  visible.     Lack  of  at- 


FLUOROSCOPY  205 

tention,  therefore,  to  this  detail  may  result  in  a  prolonga- 
tion of  the  tiuoroscopic  study,  waste  of  time,  injury  to  the 
patient  and  operator,  nervous  annoyance  and  very  often 
absolute  failure  in  the  ultimate  object  of  the  work.  If 
the  room  cannot  be  darkened,  one  must  use  the  hooded 
screen  or  work  at  night. 

Ventilation  of  the  Fluoroscopic  Room. — See  ventilation 
of  developing  room,  page  125. 

Time  Required  for  Sensitizing  the  Retina. — This  will 
vary  with  the  individual,  and  particularly  with  regard 
to  the  age  of  the  individual,  for  the  young  can  respond 
to  this  test  more  quickly  than  older  people.  In  general, 
one  should  be  in  the  dark  for  10  to  15  minutes  before 
beginning  fluoroscopic  study.  If  one  begins  in  less  time 
than  this,  there  is  likely  to  be  unnecessary  exposure  of 
patient  and  operator,  and  inefficient  and  unsatisfactory 
results  obtained. 

The  Light  for  the  Darkroom. — In  general  a  ruby  light 
is  recommended  on  the  theory  that  the  retina  becomes 
fatigued  by  the  ruby  light  and  is  therefore  more  easily 
capable  of  appreciating  the  greenish  white  light  of  the 
fluorescent  screen.  It  is  most  important,  however,  that  so 
far  as  possible  the  dim  lighting  of  the  room  should  be 
well  diffused. 

Conditions  for  Fluoroscopy. — It  must  be  clearly  recog- 
nized that  the  illumination  on  the  fluoroscopic  screen  is 
entirely  of  local  origin  and  that  the  relative  luminosity  is 
low.  For  this  reason  it  is  absolutely  necessary,  in  order 
to  observe  the  details  on  the  screen — that  is,  the  differ- 
ences in  illumination — to  exclude  light  of  every  kind 
which  does  not  originate  in  the  excited  portion  of  the 
fluorescent  material.  The  visihility  of  a  shadow  on  the 
screen  increases  with  the  difference  of  illumination  be- 
tween the  shadow  and  its  immediately  adjacent  brighter 


206  U.  S.  ARMY  X-RAY  MANUAL 

surroundings,  and  decreases  with  the  general  illumina- 
tion of  the  screen.  As  a  parallel  we  may  mention  the  case 
of  lantern  slide  projection,  where  line  drawings,  heavy 
markings,  and  things  of  great  contrast  and  reasonable  size 
may  be  projected  satisfactorily  in  a  moderately  lighted 
room  with  a  comparatively  low  power  lantern.  But  when 
finer  details  are  to  be  seen  and  more  difficult  gradations  to 
be  identified,  it  is  desirable  to  increase  to  some  extent  the 
candle  power  of  the  projector  and  to  exclude  light  from 
every  source,  such  as  windows,  doors,  etc.,  which  has  not 
passed  through  the  optical  system  to  produce  the  image. 
This  principle  is  of  even  greater  importance  in  fluoro- 
scopic work  because  the  small  crystals  excited  to  fluo- 
rescence emit  light  in  every  direction  and  always  tend  to 
illuminate  portions  of  the  screen  which  may  have  re- 
ceived no  x-rays,  so  that  we  get  a  local  cross-fire  of  true 
light  spreading  along  the  screen,  reducing  to  a  great  ex- 
tent the  visibility  of  shadows.  Screens  will  differ  in  this 
respect  to  some  extent  according  to  the  size  of  crystals  used 
and  the  smoothness  of  the  surface. 

On  account  of  this  diminution  of  detail,  owing  to  the 
nature  of  the  screen,  it  becomes  of  increasing  importance 
to  secure  as  sharp  shadows  as  possible  by  the  use  of  a  fine 
focus  tube  and  by  working  at  a  suitable  screen  distance. 

It  should  again  be  mentioned  that  the  degree  of  con- 
trast, irrespective  of  the  illumination,  is  controlled  ex- 
clusively, for  a  given  target-screen  distance,  by  the  equiva- 
lent spark  gap  of  the  working  tube.  The  contrast  will  be 
higher  the  less  penetrating  the  radiation,  and,  therefore, 
the  lower  the  spark  gap  consistent  with  proper  illumina- 
tion. 

At  a  given  spark  gap  the  only  effect  of  increasing  mil- 
liamperage  through  the  tube  is  to  increase  the  average  il- 
lumination on  the  screen,  so  that  contrast  must  be  con- 


FLUOROSCOPY  207 

trolled  by  spark  gap,  and  brightness  alone  may  be  in  part 
controlled  by  variation  of  the  tube  current.  The  effect  of 
scattering  is  even  more  disastrous  in  fluoroscopic  work  with 
thick  patients  than  it  is  in  radiographic  processes. 

As  regards  the  preparation  of  the  retina  for  fluoroscopic 
work,  undoubtedly  the  ideal  is  to  have  the  roentgenologist 
remain  in  total  darkness  for  10  minutes  before  starting 
work,  and  to  remain  in  as  nearly  complete  darkness  as  is 
possible  continuously  during  the  period  of  fluoroscopic 
examinations.  It  is,  however,  often  necessary  to  make 
a  fluoroscopic  examination  in  the  ward  or  operating  room. 
Of  various  eye  screening  methods  which  have  been  sug- 
gested, the  most  generally  recommended  is  undoubtedly 
the  bonnet  fluoroscope,  which  will  be  provided  for  use  in 
our  operating  rooms. 

For  work  in  the  wards  there  will  be  supplied  a  type 
of  automobile  goggle  in  which  celluloid  instead  of  glass 
will  be  used.  For  comparatively  dark  weather,  or  when 
working  in  the  evening  with  artificial  light,  the  red  cel- 
luloid will  probably  be  sufficient,  but  for  ward  work  when 
there  is  bright  sunlight  it  is  desirable  to  reduce  the  in- 
tensity still  further.  The  operator  can  then  insert  the 
green  celluloid  piece  back  of  the  red,  so  obtaining  an 
intensity  and  quality  of  light  reasonably  well  suited  to  the 
purpose.  As  celluloid  is  not  breakable,  and  the  goggles 
can  be  fitted  close  to  the  eye  it  seems  to  serve  the  purpose 
reasonably  well. 

In  working  with  the  surgeon  it  is  absolutely  necessary 
that  one  party  keeps  his  eyes  in  condition  for  the  best 
fluoroscopic  vision.  However  commendable  the  desire  on 
the  part  of  the  surgeon  to  see  for  himself,  he  should 
clearly  understand  that  his  selection  of  surgery  as  a  voca- 
tion has  not  modified  his  optical  organs  so  that  he  can  see 
without  taking  the  same  precautions  in  fluoroscopic  work 


208  U.  S.  ARMY  X-RAY  MANUAL 

as  are  prescribed  for  the  x-ray  operator.  It,  perhaps, 
ought  also  to  be  mentioned  that  for  a  person  who  is  par- 
tially green  blind  fluoroscopy  with  the  ordinary  screens  is 
quite  impossible,  and  men  having  this  visual  defect  ought 
not  to  attempt  work  in  this  field. 

Summarizing,  we  may  say  that  fluoroscopy  demands  (1) 
control  of  both  voltage  and  current  in  a  tube  wherever 
possible,  (2)  a  fine  focus  tube,  (3)  as  small  a  diaphragm 
as  possible,  (4)  a  good  screen,  and  (5)  eyes  sensitive  to 
screen  light  by  preparation  in  the  darkroom,  or  near  dark- 
room, for  a  sufficient  period  to  insure  good  vision. 

Note  that  one  accustomed  to  using  eye  glasses  for  read- 
ing should  not  remove  them  when  doing  fluoroscopic  work, 
as  the  necessity  for  elear  vision  is  even  greater  than  in 
other  cases. 

If  these  conditions  are  attained  with  reasonable  care, 
many  things  can  be  determined  with  the  fluoroscope  much 
more  quickly  than  with  plates,  and  the  information  se- 
cured will  be  as  accurate.  The  x-ray  operator  should  read 
carefully  the  chapter  on  protection,  and  must  assume  re- 
sponsibility for  his  own  safety. 


LOCALIZATION 

General  Considerations. — In  order  that  this  important 
work  may  be  done  expeditiously  and  with  the  desired  de- 
gree of  accuracy,  it  will  be  quite  important  for  the 
roentgenologist  to  consider  the  matter  from  the  stand- 
point of  the  greatest  service  for  the  minimum  effort,  and 
with  the  fullest  consideration  for  the  patient. 

AYhere  the  work  is  largely  fluoroscopic  the  roentgenolo- 
gist must  insist  on  having  a  properly  darkened  room  and 
be  allowed  to  remain  therein  in  order  to  keep  his  eyes  in 
proper  condition  for  his  work.  It  is  intended  that  the 
patient  should  be  prepared  outside  of  this  room,  being 
placed  upon  the  stretcher  top  of  the  x-ray  table,  and  that 
the  necessary  examination  which  precedes  the  work  of  the 
roentgenologist  should  be  done  in  daylight  and  all  neces- 
sary information  for  his  guidance  transmitted  to  him  in 
some  convenient  form.  Before  any  patient  is  placed  in 
position  he  should  see  that  the  apparatus  is  in  satis- 
factory working  condition,  that  the  accessories  necessary 
for  the  localization  he  intends  to  make  are  conveniently  at 
hand,  nor  should  he  fail  to  train  his  assistants  during 
slack  periods  in  order  that  they  may  act  promptly  and  ef- 
ficiently. 

After  the  patient  is  placed  on  the  table  it  is  desirable 
to  bring  the  affected  part  which  is  to  be  examined  some- 
where within  the  middle  third  of  the  movement  of  the 
tube  box.    A  rapid,  but  nevertheless  careful,  survey  should 

20Q 


210  U.  S.  ARMY  X-RAY  ]\IANUAL 

be  made  of  the  regions  at  some  distance  from  the  point  of 
entrance  and  emergence  of  the  projectile,  as  it  is  well 
known  that  projectiles  often  follow  tortuous  paths,  and  are 
at  considerable  distances  from  the  point  of  entry,  and  very 
often  split  into  fragments,  each  of  which  may  take  lodg- 
ment in  points  remote  from  the  main  path. 

Having  located  the  projectile  whose  presence  is  sought, 
it  will  often  be  found  that  by  use  of  parallax,  on  moving 
the  tube  slightly,  one  can  readily  determine  whether  the 
projectile  is  above  or  below  certain  bony  landmarks, 
and  sometimes  a  slight  manipulation  of  muscle  will  indi- 
cate position  with  reference  to  important  soft  tissues. 

In  the  discussion  of  methods  of  localization  following, 
an  effort  has  been  made  to  think  out  and  test  out  in  the 
laboratory  the  necessary  steps,  in  order  that  no  essential 
feature  may  be  omitted,  and  that  the  minimum  of  time 
should  be  required  in  completion  of  the  operation.  It  is 
not  intended  that  such  instruction  should  be  blindly  fol- 
lowed or  that  the  roentgenologist  should  be  prevented  from 
developing  a  procedure  which  his  experience  proves  ef- 
ficient or  desirable,  but  it  is  hoped  that  the  steps,  as  laid 
out,  will  furnish  a  working  guide  for  the  beginner,  and 
may  be  suggestive  in  the  hands  of  the  more  experienced 
roentgenologist. 

Care  in  Marking  and  Recording. — Inasmuch  as  confer- 
ence between  the  surgeon  and  the  roentgenologist  is  likely 
to  be  the  exception  rather  than  the  rule  in  military  radi- 
ology, great  care  must  be  taken  in  recording  observations. 
In  addition  to  the  written  report,  we  must,  in  the  case 
of  multiple  foreign  bodies,  identify  each  skin  mark  and 
the  corresponding  depth.  This  may  be  done  in  either  of 
two  ways :  One  may  number  each  dot  on  the  skin  and 
write  a  depth  number  beside  it.  There  is  some  danger  in 
this  case  of  confusing  the  depth  of  the  projectile  with  the 


LOCALIZATION  211 

localization  number.  The  following  is  suggested  as  an 
alternative : 

Place  around  each  skin  mark  an  indicating  symbol  that 
also  appears  on  the  record,  as  indicated  in  Fig.  98. 

The  numbers  signify  that  8  cm.  below  the  dot  in  the 
circle  there  is  a  projectile ;  3  cm.  below  the  dot  in  the 
square  there  is  another ;  and  so  forth. 

Reports. — Reports  may  be  made  in  part  on  anatomical 
charts,  if  these  are  available.  The  written  portions  should 
be  brief,  but  exact  and  explicit. 


©  B  ^  A  h   X 


Qcm  3cm  1-kcm  ^cm  6  cm  10  cm 

Fig.  98.     Method   of    distinguishing  between   skin   marks  and   de- 
noting depth  of  foreign  body  from  skin  marker. 


They  should  include : 

1.  The  designating  sj^mbol  and  the  depth,  corrected  for 
screen  position. 

2.  The  approximate  position  of  the  patient  when 
examined. 

3.  Anatomical  information. 

4.  Approximate  size  of  projectile. 

5.  Condition  of  injured  bones. 

For  marking  the  skin  in  connection  with  localization 
operations,  it  has  been  found  that  the  Finzi  ink  meets  a 
majority  of  the  tests  better  than  any  of  the  others  tested. 
The  formula  of  this  ink  is  as  follows: 

Pyrogallic  acid 1.0  gm. 

Acetone 10.0  cc. 

Liquid  chloride  of  iron 2.0  cc. 

Wood  alcohol q.s.  ad  20.0  cc. 


212  U.  S.  ARMY  X-RAY  MANUAL 

This  ink  is  rather  thin;  it  can  be  used  with  a  pen,  but 
is  not  very  satisfactory  in  this  respect.  It  makes  a  black 
mark  and  dries  in  from  thirty  to  forty-five  seconds,  de- 
pending on  the  amount  used.  It  will  smudge  slightly 
during  the  first  fifteen  minutes  after  applying,  but  leaves 
a  permanent  mark.  The  color  carries  from  gray  to  intense 
black  according  to  the  amount  used.  It  is  visible  for  forty- 
eight  hours  to  a  week,  depending  on  whether  it  is  sub- 
jected to  rubbing  in  contact  with  solid  objects  or  with 
clothing,  etc.  It  can  be  seen  through  iodine  stain  and  re- 
sists alcohol.  The  standard  skin  inker  will  make  from  ten 
to  twenty  successive  marks  without  replenishing. 

With  proper  care  as  to  the  amount  to  be  taken  on  the 
wick,  this  ink  will  be  found  to  give  satisfaction  in  use. 
Too  much  ink  will  cause  the  mark  to  run  into  the  sur- 
rounding skin  crevices,  and  the  center  of  the  mark  will 
not  be  easily  gauged.  Too  little  ink  will  not  make  a  suffi- 
ciently black  or  permanent  mark. 

Standard  Methods. — Experience  in  military  service 
during  the  present  war  has  served  to  emphasize  the  im- 
portance of  rapid  and  reasonably  accurate  methods  for 
the  localization  of  foreign  bodies.  The  ordinary  prac- 
tice of  roentgenology,  as  a  rule,  has  little  to  do  with  this 
phase  of  the  subject.  In  civil  practice  methods  could  be 
used  which  required  a  considerable  amount  of  time,  and 
it  was  usually  possible  to  consult  with  the  surgeon  and  to 
repeat  observations  to  an  extent  quite  impossible  in  the 
present  emergency.  The  localization  of  small  projectiles 
in  the  eye  had  been  developed  in  quite  a  satisfactory  man- 
ner and  no  distinct  improvement  therein  has  been  at- 
tempted. During  the  war  abroad  a  variety  of  methods  and 
appliances  have  been  used  and  the  choice  of  method  has 
been  left  largely  to  the  individual  operator,  since  circum- 


LOCALIZATION  213 

stances  prevented  systematic  attention  to  either  mechanical 
equipment  or  special  training. 

According  to  the  reports  received  from  several  excellent 
surgeons  in  active  service  at  the  front,  it  would  be  desir- 
able, and  may  even  be  regarded  as  necessary,  that  all  of 
the  injured  should  have  the  benefit  of  an  x-ray  examina- 
tion; since  it  has  been  found  that  there  are  many  cases 
where  foreign  bodies  split  off  after  entry,  or  are  in  such 
unexpected  or  peculiar  positions  that  they  can  hardly  be 
successfully  handled  without  the  evidence  available  from 
such  an  examination. 

In  order  to  work  on  such  an  extensive  scale  it  is  neces- 
sary to  consider  very  carefully  the  relation  of  x-ray  work 
to  surgery,  and  to  analyze  the  methods  which  are  to  be 
employed  with  reference  to  simplicity  and  certainty,  and 
to  pay  particular  attention  to  the  reports  and  information 
needed  by  the  surgeon  in  order  to  facilitate  his  work.  In 
this  connection  it  may  be  remarked  that  there  is  a  distinc- 
tion between  the  x-ray  requirements  in  evacuation  hospi- 
tals and  base  hospitals.  In  the  former,  speed  is  essential 
and  simple  apparatus  must  suffice.  In  the  latter,  a  more 
complete  equipment  would  be  expected.  It  may  be  well  to 
recognize  that  time  will  not  permit  the  use  of  plates  or 
films  in  the  evacuation  hospitals,  and  dependence  must  be 
put  almost  entirely  upon  fluoroscopic  work.  Consequently, 
all  arrangements  in  hospitals  near  the  front  must  conform 
to  the  conditions  imposed  by  fluoroscopy. 

As  regards  the  methods  that  have  been  selected,  it  is 
not  claimed  that  they  are  original,  and  no  effort  has  been 
made  to  get  any  universal  or  entirely  new  procedure. 
After  consideration  of  many  methods  it  has  been  deemed 
wise  to  limit  selection  to  those  that  best  meet  certain  re- 
quirements. Among  the  desirable  features  more  or  less  well 
met  by  various  methods  we  may  mention : 


214  U.  S.  ARMY  X-RAY  MANUAL 

1.  The  aj)paratus  required  should  be  simple. 

2.  The  manipulation  should  not  require  an  undue 
amount  of  skill. 

3.  The  time  required  should  be  a  minimum  consistent 
with  reasonable  accuracy. 

4.  All  operations  likely  to  lead  to  error  must  be  ex- 
cluded. 

5.  The  comfort  of  the  patient  should  be  considered. 

It  must  also  be  remembered  that  the  operator  is  an  es- 
sential part  of  the  localizing  apparatus.  It  is  therefore 
necessary  to  devise  methods  which  will  relieve  the  operator 
of  computation  and  thus  reduce  the  chances  of  error,  espe- 
cially when  an  enormous  amount  of  work  is  to  be  done 
under  trying  conditions.  Among  the  operations  giving 
opportunity  for  error  even  in  ordinarily  competent  hands 
we  may  note : 

1.  Reading  of  fine  scales. 

2.  Reading  any  scale  in  bad  light. 

3.  Making  arithmetical  computations, 

4.  Drawing  diagrams. 

5.  Changing  from  bright  light  to  read  scales  and  back 
to  fluoroscopic  work. 

Attention  has  therefore  been  directed  to  such  acces- 
sory devices  and  organization  of  steps  as  would  tend  to 
eliminate  these  contributing  sources  of  error. 

In  limiting  the  number  of  methods  for  which  provision 
is  made  there  is  no  intention  of  denying  that  others  may 
be  equally  useful  and  accurate,  and  it  is  no  criticism  of 
the  methods  or  their  advocates  that  they  have  not  been  se- 
lected. It  was  deemed  more  desirable  to  have  a  few  methods 
for  which  careful  provision  had  been  made  and  in  which 
men  could  be  well  drilled,  but  it  is  entirely  optional  with 
the  roentgenologist  which  method  he  will  use  in  any  given 
case.    It  would  be  impossible  to  provide  apparatus  for  all 


LOCALIZATION  215 

the  methods  that  might  have  been  proposed  or  advocated. 

Reference  to  the  standard  methods  has  been  made  by 
letters  instead  of  by  the  names  of  those  responsible  for 
their  development.  This  is  not  done  with  any  idea  of  de- 
tracting from  the  credit  of  the  authors  or  of  indicating 
novelty,  since  no  claim  of  priority  is  made  or  desired,  but 
simply  because  descriptions  vary  in  the  literature  and 
might  be  quite  confusing  to  the  reader  who  tries  to  follow 
directions  that  do  not  apply  to  our  apparatus. 

Before  discussing  the  various  methods  in  detail,  it  may 
well  be  pointed  out  that  refined  mathematical  accuracy  is 
not  generally  a  requisite  for  good  service  in  this  connec- 
tion. As  was  remarked  by  Lieutenant  Colonel  James  T. 
Case,  Senior  Consultant  in  Roentgenology  of  the  Ameri- 
can Expeditionary  Forces,  "This  war  is  not  being  fought 
with  bird  shot,  and  a  localization,  as  a  rule,  to  i/^  cm.  will 
be  entirely  satisfactory."  In  a  few  cases — such  as  bodies 
in  the  eye,  or  where  a  small  foreign  body  is  in  a  particu- 
larly dangerous  and  troublesome  place — greater  accuracy 
may  be  required,  but  it  is  necessary  for  the  surgeon  to 
keep  in  mind  the  fact  that  because  of  the  incision  and  the 
introduction  of  retractors  there  may  result  a  considerable 
displacement  of  the  projectile  and  it  is  often  difficult  to 
connect  its  position  with  displaced  skin  marks.  It  may  also 
be  remarked  that  in  the  majority  of  cases  a  definite  ana- 
tomical localization  should  be  given  by  experienced  and 
well-trained  roentgenologists,  which  in  many  cases  may  be 
of  greater  value  than  a  simple  depth  determination. 
AYhether  or  not  this  is  well  done  will  determine  to  a  con- 
siderable extent  the  value  of  the  x-ray  service,  and  every 
opportunity  should  be  given  the  roentgenologist  to  ascer- 
tain the  landmarks  used  in  surgery  and  to  adapt  his  work 
to  the  requirements  of  the  surgeon  using  his  data. 

The  various  localization  methods  may  be  divided  into  two 


216  U.  S.  ARMY  X-RAY  MANUAL 

distinct  groups.  In  the  first  of  these  a  mark  is  made  upon 
the  skin  and  the  distance  of  the  projectile  from  this  mark  is 
determined.  It  is  generally  assumed  that  the  skin  mark 
was  made  at  the  place  of  emergence  of  the  beam  which 
formed  a  shadow  of  the  projectile  and  that  the  tube  focus 
was  adjusted  vertically  beneath  the  projectile.  A  vertical 
line  drawn  later  through  the  skin  point  can  only  strike 
the  projectile  if  the  body  of  the  patient  is  placed  in  the 
same  position  on  the  operating  table  as  it  occupied  during 
the  x-ray  examination,  and  careful  distinction  must  be 
made  between  a  vertical  line  so  described  and  a  line  per- 
pendicular to  the  surface  of  the  skin  at  the  marked  point. 
The  amount  by  which  the  surgeon  may  miss  the  projectile 
by  failure  to  get  a  correct  sight  line  increases  materially 
with  increased  depth  of  the  projectile  and  with  decreased 
dimensions,  and  some  idea  of  the  size  of  the  body  sought 
should  always  be  given.  Much  greater  care  will  surely  be 
needed  in  the  localization  of  the  smaller  bodies. 

In  the  other  group  of  methods  some  material  guide  is 
given  to  the  surgeon  to  assist  him  during  operation.  As 
a  rule  these  require  more  time,  both  on  the  part  of  the 
roentgenologist  and  of  the  surgeon's  assistants.  They  are 
naturally  better  adapted  to  the  work  done  in  the  perma- 
nent or  base  hospitals. 

After  receiving  reports  from  both  surgeons  and  roent- 
genologists abroad,  and  after  conference  with  Lieutenant 
Colonel  James  T.  Case,  at  which  appliances  and  methods 
were  carefully  considered,  it  was  decided  by  the  Surgeon 
General's  Office  to  adopt  and  provide  apparatus  for  the 
following  methods: 

A.  Two  wire,  double  tube  shift  method. 

B.  Parallax  method. 

C.  Tube  shift  method  with  mechanical  triangulation. 


LOCALIZATION  217 

D.  Profondometer. 

E.  Hirtz  compass  with  accessory  devices. 

F.  Cannula  and  trochar  with  harpoon. 

It  happens  that  the  first  three  of  these  are  simple  depth 
measurements,  although  B  may  give  more  than  one  depth, 
whereas  the  last  three  may  be  used  to  give  more  or  less 
definite  guidance  to  the  surgeon  during  operation. 

It  is  assumed  that  the  majority  of  the  work  will  be  done 
with  the  standard  x-ray  table  by  fluoroscopic  methods  and 
with  the  tube  below  the  table.  The  tube  box  is  movable 
in  two  directions  as  in  the  usual  trochoscope  and  is  pro- 
vided with  a  double  shutter  giving  a  diamond-shaped  open- 
ing with  the  diagonals  parallel  and  perpendicular  to  the 
length  of  the  table  and  also  with  an  adjustable  slit,  under 
separate  control,  parallel  to  the  length  of  the  table.  The 
tube  box  runs  freely  and  may  be  locked  in  any  position 
against  both  lateral  and  longitudinal  movement,  and  is 
also  provided  with  a  simple  means  for  fixing  the  amount 
of  tube  shift  for  a  particular  purpose  or  for  measuring 
any  shift  from  a  fixed  position. 

The  fluoroscopic  screen  is  carried  by  a  ball-bearing  car- 
riage mounted  on  the  table  rails,  and  provision  is  made  for 
a  movement  parallel  to  the  table,  for  rotation  about  a  ver- 
tical axis  and,  also,  for  a  vertical  shift.  Each  of  these 
movements  may  be  prevented  by  a  suitable,  convenient  lock. 
The  fluoroscopic  screens  are  perforated  with  a  small  hole 
through  which  a  marking  device  may  be  inserted  to  mark 
the  skin  in  the  vertical  ray.  When  this  ray  is  spoken  of 
it  is  assumed  that  the  table  will  be  substantially  in  a  hori- 
zontal position  and  that  a  line  joining  the  target  with  the 
center  of  the  diaphragm  will  be  perpendicular  to  the  plane 
in  which  the  tube  may  move.  The  opening  in  the  screen 
also  serves  a  very  convenient  purpose  in  temporarily  fix- 


218  U.  S.  ARMY  X-RAY  MANUAL 

ing  in  position  the  scales  and  other  pieces  of  apparatus 
which  it  is  desired  to  use  on  the  fluoroscopic  screen. 
Definitions — 

Central  Bay. — The  ray  passing  through  the  center  of 
the  limiting  diaphragm,  which,  when  the  tube  is  fixed  with 
reference  to  the  diaphragm  holder,  will  change  its  direc- 
tion with  each  tilt  or  movement  of  the  tube  and  its  mount- 
ing. 

Vertical  Ray. — The  central  ray  when  the  tube  is  beneath 
the  table,  and  the  target  is  so  adjusted  that  the  line  joining 
the  focal  spot  of  the  target  with  the  center  of  the  dia- 
phragm opening  is  vertical. 

Note. — There  has  been  a  good  deal  of  discussion  with 
reference  to  the  correction  for  depth  on  account  of  the 
thickness  of  the  glass  over  the  fluoroscopic  screen.  As 
outlined  in  this  manual,  there  is  only  one  case  where  this 
correction  is  of  any  importance  or  even  applies.  In 
Methods  A  and  C  it  should  be  remembered  that  the  eye 
of  the  operator  is  directed  at  the  shadow  on  the  screen  and 
that  the  distance  measured  on  the  lead  glass  in  Methods 
A  and  C  represents  a  length  on  the  screen  itself  so  that 
when  the  screen  is  in  contact  with  the  marked  point  on  the 
skin  we  may,  in  Methods  A  and  C,  ignore  the  glass  thick- 
ness. 

In  case,  by  reason  of  curvature  of  the  body,  the  hori- 
zontal screen  cannot  be  brought  in  contact  with  the  skin 
mark,  it  will  be  necessary  to  allow  for  the  distance  between 
the  screen  and  the  skin,  and  this  may  be  a  very  decided  cor- 
rection. The  simplest  way  in  which  this  may  be  done  is 
undoubtedly  to  push  the  graduated  marking  device  which 
is  used  with  the  perforation  in  the  screen  through  to  con- 
tact with  the  skin,  grasp  it  at  the  surface  of  the  screen 
with  the  thumb  and  foreflnger  and  immediately  on  with- 
drawal read  and  record  the  distance  from  the  glass  surface 


LOCALIZATION  219 

to  the  skin.  This  would  give  a  clei)th,  not  below  the 
screen,  but  below  the  top  of  the  lead  glass.  Since  this 
glass  is  generally  about  one-half  centimeter  thick  it  will 
suffice  to  use  one-half  centimeter  or  one  division  less  than 
is  actually  measured  as  a  subtractive  correction. 

In  Method  E,  when  the  Hirtz  compass  is  used  fluoro- 
scopically,  care  must  be  taken  to  add  to  the  depth  meas- 
urement of  the  projectile  the  thickness  of  the  lead  glass, 
if  the  method  of  determining  marker  depths  through  the 
hole  in  the  screen  is  used.  In  other  words,  in  the  Hirtz 
compass,  the  four  depths  must  all  be  measured  from  the 
same  plane,  although  this  is  not  the  plane  of  the  arms 
when  the  compass  is  set  up. 

Method  A. — Probably  the  most  generally  used  fluoro- 
scopic method  is  that  designated  in  our  work  as  Method  A. 
This  method  was  proposed  since  the  beginning  of  the  war 
by  Professor  Strohl  of  the  French  Roentgenological  Serv- 
ice. It  is  extremely  rapid,  reasonably  accurate,  and,  as  it 
requires  a  minimum  of  manipulation,  it  is  likely  to  be  the 
method  of  preference  for  work  in  the  evacuation  hospitals. 
In  this,  as  in  the  other  methods  here  described,  it  is  as- 
sumed that  the  standard  apparatus  adopted  by  the  x-ray 
division  of  the  army  will  be  used. 

The  apparatus  supplied  for  the  standard  equipment  in- 
cludes a  substantial  brass  frame,  carrying  two  wires  firmly 
attached  across  two  opposite  corners  and  protected  by  a 
thin  sheet  of  aluminum,  Fig.  99.  These  wires  move  with, 
the  tube  box  and,  when  the  diamond-shaped  shutter  is 
wide  open,  they  would  cast  shadows  upon  the  fluorescent 
screen.  These  shadows,  of  course,  move  with  the  tube  box. 
After  bringing  the  shadow  of  the  projectile  to  the  center  of 
the  fluoroscopic  screen,  and  marking  the  skin  through  the 
opening  provided,  the  operator  places  in  position  a  small 
celluloid  scale  with  two  sliders.     He  then  shifts  the  tube 


220 


U.  S.  ARMY  X-RAY  MANUAL 


until  the  shadow  of  one  of  the  wires  carried  by  the  box 
coincides  with  the  now  displaced  shadow  of  the  projectile, 
and  adjusts  one  of  the  sliders  to  mark  this  position ;  then, 


■J  2- . 


1    2  S   4   5  ^  7  8  9  10  l"}  18  13  14  15  16  17  18  1920 


'I'l'I'l'I'ITI'I'l'iTI'ITF 

21  28 23 2425 2627 888© 30 3i  32533435  56 


-r-r-i-t-r  i-r' ;-■!•- VT-i- 


FiG.  99.     Apparatus  for  Method  A  consisting  of  cross  wire  holder, 
double  slider,  and  special  rule. 


shifting  in  the  opposite  direction,  and  leaving  the  first 
slider  and  the  center  of  the  device  fixed,  the  shadow  of 
the  other  wire  is  brought  to  coincidence  with  that  of  the 


LOCALIZATION  221 

projectile,  and  the  second  slider  fixed  accordingly.  The 
distance  between  tliese  two  markers  is  in  a  definite  pro- 
portion to  the  distance  from  the  fluoroscopic  screen  to  the 
projectile  in  question,  and  by  means  of  a  properly  designed 
scale  the  depth  in  centimeters  and  fractions  of  a  centi- 


^J^F  fi    =-    Screen 


,       .    CJ     A      \B    C     \Af  , 

V-r-/     vi~7    Vt""/ 


r,  Fo 


L 


-^D 


Pz     Pi 

Fig.  100.  Principle  of  the  Method  A  above.  Simple  slider  for 
measurement  of  the  distance  between  the  two  images  shown  below 
diagram. 

meter  can  be  read  directly.  In  case  the  central  point  of 
the  screen  is  not  in  contact  with  the  skin,  where  a  mark 
is  made,  it  will  be  necessary  to  correct  for  the  distance 
between  the  skin  and  the  screen.  This  is  not  necessary 
when  the  point  marked  is  actually  in  contact  with  the  hori- 
zontal screen. 


222  U.  S.  ARMY  X-RAY  IMANUAL 

On  account  of  its  extreme  simplicity  and  the  fact  that 
only  a  single  measurement  has  to  be  made,  and  that  the 
target-screen  distance  need  not  be  known,  this  method  has 
been  placed  first  in  order  of  preference. 

The  principle  of  method  A  is  illustrated  by  Fig.  100, 
which  shows  a  vertical  section  through  the  foreign  body  P, 
and  the  target  focus  Fq.  B  is  the  foot  of  a  perpendicular 
from  Fq  on  the  line  AC.  A  and  C  are  the  two  metal  wires 
rigidly  attached  to  the  tube  box  and  equidistant  from  B. 
Let  Pq  be  the  shadow  of  P  by  the  vertical  ray.  If  we  shift 
the  target  parallel  to  the  screen  and  to  the  left,  both  A 
and  C  being  fixed  to  the  box,  they  must  move  with  it  and 
at  a  certain  point  F^,  Cj_  and  P  will  fall  on  the  same  line, 
and  the  shadow  of  C  in  the  position  Oj  will  coincide  with 
that  of  P  at  Pi-  Likewise,  shifting  the  target  to  the  right 
will  bring  A^,  Fo  and  P  into  the  same  straight  line,  FJt^P^. 

Since  F^P^  is  parallel  to  F^C, 

F.P,  "         ''        "    F,A, 

and       P,P,  ''         "        ''AC, 

the  triangles  FqAC  and  PPJ'2  are  similar.  Consequently 
PJ>  =  depth  of  P  below  P^  =  d,  is  in  the  same  proportion 
to  P1P2  as  BFq  is  to  AC.     Or  we  may  write, 

Depth  of  projectile  Height  of  B  above  F^ 

Image  shift  Distance  between  A  and  C 

The  latter  ratio  is  constant  and  is  fixed  in  the  set-up 
on  the  regular  army  x-ray  table. 

Hence  d  =  image  shift  multiplied  by  a  constant,  k, 
that  is 

d  =  P^P^  X  k. 

It  we  read  P1P2  in  centimeters  and  multiply  by  k,  d  will 
be  found  in  centimeters. 

The  special  sliding  markers,  described  above,  are  shown 


LOCALIZATION 


223 


in  Figs  99  and  100.     The  center  pin  drops  into  the  hole 
in  the  lead  glass  and  prevents  slipping. 

To  avoid  multiplication  a  special  scale  is  provided.  The 
distance,  P^Pz,  read  on  this  scale  gives  the  required  depth. 
This  scale  is  not  a  centimeter  scale,  hut  the  readings  give 

m 


Fig.  101.  Successive  appearances  on  fluoroscopic  screen  in  Met- 
hod  A.  (1)  Shadow  of  projectile  with  small  diaphram  at  central 
point  of  scheen.  (2)  Rectangular  diaphragm  replaced  by  slit  open- 
ing shadow  of  wires  at  right  and  left.  (3)  Tube  has  been  shifted  to 
the  left,  bringng  shadow  of  projectile  and  right  hand  wire  to  coinci- 
dence. (4)  Reversed  shift  of  tube,  bringing  left  wire  and  projectile 
shadow  to  coincidence. 

depth  in  centimeters  and  fractions  thereof  for  a  proper 
height  adjustment  of  the  tube. 

Fig.  101  shows  screen  shadows  in  steps  of  this  method. 
In  (1)  is  seen  shadows  in  central  ray;  (2)  shows  open 
slit  and  shadows  of  wires;  (3)  shows  coincidence  of  shadow 
and  right  hand  wire,  and  (4)   points  for  measurement. 

Operating  Instructions  for  Method  A — 

1.  Make  a  general  survey  of  the  region  to  be  examined, 
noting  the  number  and  approximate  position  of  the  pro- 


224  U.  S.  ARMY  X-RAY  MANUAL 

jectiles,  and  the  condition  of  tlie  bones  as  to  fracture  or 
projectile  injury,  dislocations,  etc. 

2.  Bring-  the  shadow  of  the  projectile  which  is  to  be  lo- 
calized, using  a  small  shutter  opening,  upon  the  perfora- 
tion in  the  screen,  and  lower  the  screen  until  it  is  in  con- 
tact with  the  body. 

3.  Using-  the  special  skin  marker,  mark  the  skin  carefully 
throug-h  the  perforation,  and  observe  whether  the  skin 
point  is  in  contact  with  or  at  some  distance  from  the  un- 
der side  of  the  screen.  If  the  latter,  immediately  note 
the  correction  needed. 

4.  Open  the  diamond-shaped  shutter  fully,  and  close  the 
slit  to  a  convenient  width. 

5.  Insert  the  pin  of  the  small  celluloid  double  sHder  in 
the  perforation  in  the  screen,  the  screen  to  be  locked 
against  all  movement.  Shift  the  tube  to  the  right  or  left, 
watching  the  shadows  of  the  cross  wire,  which  is  initially 
seen  at  the  extreme  edge  of  the  slit  opening,  until  these 
shadows  become  coincident.  Leave  the  tube  at  rest,  and 
adjust  the  inner  edge  of  the  slider  to  coincidence  with  the 
shadow.  Reverse  the  shift  of  the  tube,  and  do  the  same 
for  the  second  slider. 

6.  Remove  the  slider  attachment,  and,  by  means  of  the 
special  boxwood  scale  provided,  read  the  distance  between 
the  inner  edges  of  the  two  sliders,  and  record  this  reading 
as  depth  in  centimeters. 

7.  Identify  this  skin  mark,  provided  more  than  one  lo- 
calization is  to  be  made,  and  immediately  enter  everything 
on  the  record. 

Method  B. — This  method  utilizes  the  optical  principle 
of  parallax  and  may  be  carried  out  with  extremely  simple 
apparatus,  although  a  more  elaborate  device  has  been 
provided.   If  one  observes  the  shadow  of  a  projectile  upon 


LOCALIZATION  225 

the  fluoroscopic  screen,  while  the  tube  is  movinf?  and  the 
projectile  is  ver}^  close  to  the  screen,  the  shadow  movement 
for  a  given  tube  shift  will  be  very  slight  and  the  farther 
the  body  is  removed  from  the  screen  the  greater  will  be 
the  extent  of  the  shadow  motion.  If  we  adjust  a  suitable 
opaque  body  outside  of  the  patient  until  its  shadow  moves 
the  same  distance  for  a  definite  tube  shift  as  was  moved 
by  the  shadow  of  the  projectile  for  the  same  tube  dis- 
placement, the  auxiliary  body  must  then  be  as  far  from 
the  screen  as  the  projectile  whose  depth  is  sought. 

In  the  case  of  a  projectile  in  the  abdomen,  so  far  from 
the  lateral  boundary  of  the  body  as  to  preclude  simul- 
taneous observation 
of  the  indicator  shad- 
ow and  that  of  the 
projectile,  the  a  d- 
justment  of  the  latter 
may    be    made    after 

the  patient  has  been       Fig.  102.    Ruled  celluloid  sheet  to  in- 
.  dicate   equality   of    displacement   of   two 

removed,     provided   shado^vs  in  Method  B. 

the   screen   has   been 

locked  against  vertical  motion  so  as  to  remain  at  the  same 
distance  from  the  target  as  before.  Generally,  however,  the 
indicator  may  be  moved  up  and  down  in  a  plane,  passing 
through  the  projectile  and  perpendicular  to  the  axis  of  the 
body,  close  enough  to  the  patient  to  permit  free  motion  and 
allow  both  shadows  to  be  seen  at  once. 

By  means  of  parallel  lines  ruled  on  a  transparent  piece 
of  celluloid.  Fig.  102,  it  is  fairly  easy  to  ascertain  when 
equality  of  motion  of  the  two  shadows  is  secured.  In  the 
more  complete  apparatus  furnished  for  this  work,  Fig. 
103,  it  is  possible  to  mark  the  skin  at  the  entrance  and 
emergence  point  of  the  vertical  ray  and  also  along  a  con- 
tinuation of  the  rod  carrying  the  special  indicator.     This 


226 


U.  S.  AR]\IY  X-RAY  IMANUAL 


really  gives  three  independent  depths  with  some  corre- 
sponding: advantage  to  the  snrgeon. 

The  principle  of  this  method  is  shown  in  Fig.  lO-i,  where 

FqFq  represents  the  vertical  ray, 

P  '^  *'    foreign  body, 

B  ''  "an    auxiliary    body    opaque   to    the 

rays  and  adjustable  at  will. 

The  shadows  of  P  and  B  are  shown  as  though  they  were 


EiG.  1U3.     Schematic  drawing  of  parallax  localizer. 


in  the  plane  of  the  paper,  but  this  is  not  the  actual  case, 
as  B  will  be  quite  outside  this  plane. 

If,  now,  the  target  is  moved  toward  the  left  to  P^,  the 
shadows  appear  at  P'  and  B' ,  and  P^B'  is  greater  than 
PqP^  if  B  is  farther  from  the  screen  than  P. 

By  raising  or  lowering  B  a  position  may  be  found 
where,  on  shifting  the  tube,  the  shadow  of  B  and  P  move 
at  the  same  rate.  Then  B  and  P  are  the  same  distance 
below  the  screen.  The  ruled  sheet  of  celluloid,  Fig.  102,  is 
a  convenience  in  making  sure  that  P  and  B  move  the  same 
amount  when  a  convenient  tube  shift  is  made 


LOCALIZATION 


227 


Apparatus. — The  apparatus  may  consist  essentially  of 
the  following-  parts:     Fig.  103. 

A  base  of  suitable  size  carries  a  vertical  post,  V.  Sliding 
on  this  post  are  two  rods  at  right  angles  to  it  that  may  be 
adjusted  vertically  at  will.     The  upper  of  these  is  not  ad- 


mz 


Scr-een 


m'P 


/ 


// 


/ 
/ 
/ 
/ 

/       / 
/      / 
/      / 

/ 


=^ 


/ 


/ 


/ 


/ 


/ 
/ 


Fig.  104.  Principle  of  parallax  metliod.  Auxiliary  body,  B,  be- 
low P  and  distal  from  the  screen  shows  greater  shadow  displacement 
to  B, 


justable  laterally,  so  tbat  the  ring,  "R,  is  at  a  fixed  distance 
from  the  upright,  T.  The  other  rod  carries  a  ball,  B. 
This  may  be  perforated  to  permit  of  a  projecting  skin 
marker.  B  may  be  shifted  in  two  directions  at  will. 
"When  adjusted  so  that  its  shadow  moves  at  the  same  rate 
as  that  of  P,  when  the  tube  is  shifted,  the  distance  be- 


228 


U.  S.  ARMY  X-RAY  MANUAL 


tween  the  rods,  d,  is  the  depth  of  P  below  the  ring,  E. 
This  is  true  independently  of  the  screen  position. 

By  using  three  scales,  D,  H,  and  V,  we  may  find  the  dis- 
tance from  the  skin  to  P  in  three  directions,  viz.,  PR,  PB 
and  PC.    In  all  cases  d  and  h  should  be  observed  and  B 


Fig.  105.     Apparatus  for  Metliod  B. 

and  B  marked.     If  the  opening  in  the  base,  C,  is  used 
in  centering,  BC  and  PB  are  at  90°. 

The  parallax  method  may  be  utilized  with  either  im- 
provised apparatus  or  with  the  more  complete  instrument. 
In  using  the  latter  the  operator  must  bear  in  mind  the 
fact  that  the  accuracy  of  this  instrument  will  depend  to 
a  considerable  extent  upon  the  care  with  which  it  is  used. 
For  example,  if  either  of  the  horizontal  projecting  arms 
becomes  bent  the  readings  will  be  in  error,  as  it  is  as- 


LOCALIZATION  229 

sumed  that  they  are  strictly  parallel  and  that  both  are 
perpendicular  to  the  vertical  support  rod.    The  equipment 
supplied  for  use  in  Method  B  is  shown  in  Fig.  105. 
Operation  of  Method  B — 

1.  Make  a  general  survey  as  previously  directed. 

2.  Place  the  parallax  instrument  in  position  so  that  the 
vertical  ray  through  the  projectile  falls  on  the  center  of 
the  ring.  This  ring  is  to  be  concentric  with  the  one  around 
the  opening  in  the  base  of  the  instrument.  Have  B  drawn 
back  out  of  the  way  when  placing  the  instrument. 

3.  Lower  the  ring  to  contact  with  the  skin  and  bring  the 
screen  down  as  low  as  the  part  examined  will  permit. 

4.  Move  rod  B  forward  as  near  the  skin  as  free  vertical 
motion  will  allow,  and  so  place  the  fluoroscopic  screen,  if 
possible,  as  to  allow  the  shadow  of  P  and  that  of  the  end  of 
B  to  show  on  the  screen. 

5.  Place  the  piece  of  celluloid,  ruled  with  lines  three 
centimeters  apart,  so  that  one  of  these  lines  passes  through 
the  shadows  of  both  P  and  B. 

6.  Shift  the  tube  until  the  shadow  of  P  falls  on  another 
of  the  ruled  lines,  clamp  the  tube  in  position,  and  then 
alter  the  height  of  B  until  its  shadow  falls  on  the  same  line 
as  that  of  P.  Do  not  try  to  follow  the  motion  of  both 
shadows  at  once. 

7.  Check  your  setting  after  clamping  B  in  position  by 
shifting  the  tube  back,  and  see  whether  both  shadows  fall 
on  the  same  ruled  line  as  before. 

8.  Push  B  forward  to  contact  with  the  skin,  and  mark  by 
the  projecting  marker  passing  through  B. 

9.  Carefully  remove  the  instrument,  being  sure  that 
both  horizontal  rods  are  clamped  in  position,  and  read  the 
three  scales  indicating  two  vertical  depths  and  one  hori- 
zontal. Record  these  with  the  same  additional  data  as  in 
Method  A. 


230  U.  S.  ARIMY  X-RAY  INIANUAL 

In  using  the  parallax  instrument  as  described,  the  depth 
indicated  is  from  the  ring  R,  which  always  must  be  brouglit 
down  to  the  skin  quite  irrespective  of  the  position  of  the 
fluoroscopic  screen. 

Simpler  Method  of  Operation. — In  many  cases  one  may 
utilize  a  simple  substitution  method  as  follows: 

Having  the  shadow  in  the  vertical  ray  and  having 
marked  the  skin,  shift  the  tube  until  the  shadow  of  P  has 
moved  a  convenient  distance  on  the  screen.  Lock  the  tube 
box  in  position  and  register  the  new  shadow  position  with 
the  edge  of  a  small  piece  of  lead  laid  on  the  screen.  Lock 
the  screen  against  vertical  motion  and  to  the  rail.  It  can 
then  be  swung  to  one  side,  the  patient  moved  out  of  the 
range  of  the  vertical  ray,  and  the  screen  swung  back  to 
its  former  position,  as  determined  by  use  of  a  small  shut- 
ter opening.  The  shutter  may  then  be  opened,  the  marker 
passed  through  the  perforation  in  the  screen,  and  adjusted 
so  that  the  shadow  of  its  lower  end  reaches  the  previously 
placed  marker  on  the  screen.  Its  projection  below  the 
screen  is  the  depth  sought. 

In  using  the  method  of  parallax  it  may  be  inconvenient 
or  impossible  to  get  a  good  view  of  the  shadow  of  the  pro- 
jectile and  of  the  adjustable  body  at  the  same  time.  It 
should  be  remembered  that  if  the  shift  of  the  image  has 
been  measured,  as  in  the  method  just  described,  the  patient 
may  be  removed  without  vertical  displacement  of  the 
screen,  and  the  auxiliary  body  as  B  may  be  adjusted  to 
give  the  displacement  of  shadow  for  the  same  tube  shift, 
but,  in  this  case,  the  depth  in  a  horizontal  direction  can- 
not be  determined. 

Method  0. — The  single  tube  shift  method  with  triangu- 
lation  has  appeared  in  a  great  variety  of  forms.  Some 
of  these  involve  the  drawing  of  diagrams  and  the  use  of 
algebraic  computation.     In  many  cases  the  apparatus  was 


LOCALIZATION 


231 


desiofiiod  to  work  at  a  fixed  tube-screen  distance,  which  has 
certain  disadvantages.  The  principle  of  the  method  is 
shown  in  Fig.  106. 

Let  F^y  be  the  target  in  such  a  position  that  the  vertical 
ray  at  right  angles  to  the  plane  of  the  tube  movement 

P      P 


Fig.   106.     Principle  of   single   tube   shift  method. 


projects  the  shadow  of  the  foreign  body,  P,  on  the  hole  in 
the  screen. 

Shifting  the  tube  to  F^^,  there  will  result  an  image  shift 
to  Pi,  and  the  triangles  PqP^P  and  F^F^P  are  similar. 
Also  F^QP-^  is  similar  to  each. 


Therefore  P^Q 


PP. 


-or    PPo    =   PoPx    X 


P^Q 


P,P,  -    -^   —   -^^-   "  F,Q 
i.  e.,  depth  of  foreign  body  =  image  shift  x  target-screen 
distance  divided  by  sum  of  tube  shift  and  image  shift. 
Where   no    auxiliary   apparatus   is   supplied,   one   must 


232 


U.  S.  ARMY  X-RAY  IMANUAL 


B 


Fig.  107.     Wall   meter    or   indicator    for   tube    shift  method,   also 
showing  method  of  using  adjustable  double  slider  caliper. 


LOCALIZATION  233 

measure  the  various  lengths  by  a  scale  and  make  a  numeri- 
cal computation.  This  may  be  made  easier  by  the  use  of 
special  devices. 

1.  A  fixed  tube  shift  of  10  or  15  cm.  may  be  used  or  an 
image  shift  of  an  exact  number  of  centimeters. 

2.  A  fixed  target-screen  distance  may  be  used.  This  is 
not,  however,  alwaj-s  convenient. 

3.  The  exact  set-up  of  Fig.  106  may  be  reproduced  by 
use  of  a  device  shown  in  Fig.  107,  which  may  be  supplied 
in  case  of  a  desire  to  use  this  method. 

This  device  consists  of  two  straight  bars,  A  and  B,  at 
right  angles  to  each  other.  B  carries  an  adjustable  slider, 
R.  A  carries  two  sliders,  E  and  G.  E  is  not  moved  after 
one  adjustment  unless  a  new  table  is  used.  The  slider,  G, 
has  notches,  1,  2,  etc.,  1  cm.  apart,  and  a  slider,  P^,  wdth  a 
latch  engaging  these  notches.  A  scale,  >8^,  with  its  zero 
point  at  the  upper  end  is  carried  by  G.  A  lug  at  II  is  in 
line  with  the  zero  of  G. 

If,  now,  DR  =  tube  shift, 

GH  =  target-screen  distance, 
P-^O  =  image  shift, 
then  a  straight  line,  P^D,  will  cross  the  scale,  >S^,  at  the 
depth  of  the  foreign  body  below  the  screen.  The  instru- 
ment should  be  fastened  to  the  wall  in  a  convenient  place 
and  the  measurements  needed  should  be  made  by  a  caliper, 
thus  avoiding  any  reading  of  scales  except  the  final  depth. 

If  in  the  particular  case  illustrated,  the  image  shift  is 
4  cm.  and  the  zero  point  of  scale,  S,  is  set  above  H  an 
amount  equal  to  the  target-screen  distance,  and  DH  is  the 
tube  shift  for  an  image  shift  of  4  cm.,  a  string  drawn  as 
indicated  will  cross  the  scale  at  a  point  P.  The  scale  read- 
ing at  this  point  is  the  depth  sought. 

"When  using  the  standard  table  the  slider,  E,  is  ad- 
justed so   that   a  length   measured   on   the   screen-carrier 


234  U.  S.  ARMY  X-RAY  MANUAL 

support  will  show  how  much  above  E  we  must  place  G  in 
order  that  GH  may  represent  the  target-screen  distance. 

It  will  be  observed  that  this  instrument  serves  to  repro- 
duce tube  and  image  positions  as  actually  observed  by  the 
roentgenologist ;  i.  e.,  one  vertical  ray  in  which  the  skin 
is  marked,  and  one  oblique  ray  whose  intersection  with  the 
former  corresponds  to  the  distance  of  the  projectile  from 
the  screen. 

An  accessory  device  is  also  supplied,  consisting  of  a 
strip  of  celluloid  with  a  pin  centering  in  the  perforation 
of  the  screen,  and  having  centimeter  divisions  clearly 
marked  both  ways  from  the  center;  making  it  quite  easy 
to  secure  an  exact  number  of  centimeters  displacement. 

There  is  a  considerable  advantage  in  making  the  distance 
the  image  is  shifted  a  definite  number  of  centimeters,  and 
measuring  the  tube  shift,  since  the  relative  error  in  meas- 
uring the  small  length  of  image  shift  is  greater  than  that 
in  measuring  the  long  tube  shift. 

"When  supplied  with  the  accessories  indicated  above,  this 
method  becomes  as  expeditious  as  others,  and  is  as  accu- 
rate as  any  of  the  depth  methods. 

In  the  single  tube  shift  method  there  are  various  pro- 
cedures which  may  be  used.  They  all  require  essentially 
the  same  data,  namely,  (1)  tube  shift,  (2)  image  shift,  (3) 
target-screen  distance.  If  these  distances  are  measured  to 
scale  in  centimeters,  it  is  possible  to  compute  the  end  re- 
sult. 

The  apparatus  supplied  for  this  method  includes  a  scale 
whereby  a  definite  image  shift  may  be  made,  if  that  is  de- 
sired by  the  operator.  There  is  also  a  provision  for  a 
definite  tube  shift  of  either  10  or  15  cm.  on  the  standard 
table  and  for  the  measurement  of  any  tube  shift,  if  the 
operator  desires  to  make  the  shift  of  the  image  a  definite 
amount — the  procedure  generally  advised. 


LOCALIZATION 


235 


Fig.  108.     Apparatus  for  Metliod  C. 


236  U.  S.  ARMY  X-RAY  MANUAL 

The  complete  equipment,  including  the  reproducing  de- 
vice or  wall  meter  and  accessories,  is  shown  in  Fig.  108. 
Specific  Instructions  for  Method  C — 

1.  Proceed  as  in  other  cases  with  regard  to  bringing  the 
shadow  in  the  vertical  ray  to  the  center  of  the  screen  or 
on  the  perforation,  and  mark  the  skin  as  usual. 

2.  Place  the  small  celluloid  centimeter  scale  in  position 
on  the  screen,  so  that  its  length  is  approximately  parallel 
to  the  rails  of  the  table.  Bring  the  ring  lock,  on  the  rail 
outside  of  the  carriage,  against  the  projecting  stop  on  the 
right-hand  side,  while  the  tube  is  in  first  position.  Shift 
the  tube  to  the  left,  watching  the  shadow  of  the  projectile 
on  the  scale  until  it  has  moved  the  largest  number  of  full 
centimeters  permitted  by  full  opening  of  the  diaphragm 
(a  narrow  slit  may  be  used  to  sharpen  the  image),  and  lock 
the  tube  carriage  in  this  position. 

3.  Having  the  slider,  E,  on  arm  A  of  the  instrument, 
previously  set  according  to  instructions  on  page  163,  place 
the  outside  of  the  end  piece  of  the  caliper,  C,  against 
the  right  angle  projection  on  the  tube  carriage,  and 
slide  the  inner  of  the  two  movable  projectors  out  until  it 
comes  in  contact  with  the  fixed  ring  on  the  table.  Then 
place  the  fixed  projector  of  the  caliper  at  the  top  of  the 
tube  of  the  screen  carrier,  and  bring  the  outside  movable 
piece  up  to  contact  with  the  sliding  sleeve,  Fig.  109. 

4]  Move  the  slider  on  G,  Fig.  107,  the  number  of  centi- 
meters by  which  the  image  was  shifted — as  four  in  the  fig- 
ure. Place  the  inner  movable  clip  of  the  caliper  against  H 
and  move  the  slider  E  on  B  io  contact  with  the  fixed  end 
and  lock  in  position.  Place  the  fixed  end  of  the  caliper 
on  the  top  of  E  and  bring  G  down  to  contact  with  the  outer 
slider.  A  string  drawn  across,  as  indicated  in  the  figure, 
gives  the  depth  of  the  projectile  below  the  fluoroscopic 
screen. 


LOCALIZATION 


237 


5.  In  case  the  screen  was  not  in  contact  with  the  skin 
at  the  point  of  marking,  determine  the  correction  by  the 
usual  means. 


Fig.  109.  Use  of  double  slider  caliper  in  measuring  target-screen 
distance — localization^  MetJiod  C. 

If  this  instrument  is  used  as  directed  it  will  be  observed 
that  there  are  no  scales  to  read  before  the  end  result  and 
no  computations.  It  is  essential  that  the  position  of  E  be 
determined  for  the  apparatus  used  and  firmly  fixed. 


238  U.  S.  ARMY  X-RAY  INIANUAL 

All  of  the  second  group  of  methods  require  somewhat 
different  manipulation  and  an  added  amount  of  data  which 
may  give  the  surgeon  rather  more  definite  indications  and 
assist  him  materially  in  many  cases. 

Method  D. — This  method  has  been  described  by  Major 
Joseph  M.  Flint  in  The  Military  Surgeon  of  March,  1917, 
and  while  the  method  is  not  new  in  principle  it  had  not 
been  generally  used  heretofore,  as  apparatus  for  its  ap- 
plication was  rarely  available.  It  consists  essentially  in 
securing  three  lines  of  sight  through  the  body,  each  of 
which  is  to  pass  through  the  projectile.  The  points  where 
the  rays  enter  and  emerge  in  establishing  these  lines  are 
plainly  marked  on  the  skin.  Two  pieces  of  flexible  metal, 
such  as  a  composition  of  tin,  are  hinged  together  in  the 
middle  and  placed  around  the  body  in  the  plane  of  the 
skin  marks  and  made  to  conform  to  the  shape  of  the  body. 
The  strip  is  marked,  showing  the  distance  that  one  un- 
hinged end  overlaps  the  other,  and  the  skin  marks  are 
transferred  to  this  metal  band.  Carefully  removing  the 
latter  from  the  body,  it  may  be  laid  down  on  a  card  or 
a  sheet  of  paper,  and  by  bringing  the  overlapping  end  to 
its  original  position  a  tracing  with  a  pencil  will  show  the 
outline  of  the  body  in  the  plane  of  examination.  The  skin 
mark  positions  are  then  transferred  to  the  diagram  and 
we  have  an  approximate  duplicate  of  the  shape  of  the  body 
and  the  locations  of  the  external  skin  markings. 

If,  on  this  diagram,  Fig.  110,  one  numbers  the  skin 
marks  in  series,  1,  2,  3,  4,  5.  and  6^  and  joins  1  and  4,  2 
and  5,  and  3  and  6,  and  if  the  work  has  been  strictly  ac- 
curate, that  is,  if  the  sight  lines  were  properly  established, 
and  if  the  shape  of  the  body  did  not  change  by  change  of 
position  when  the  band  was  put  on,  supposing  the  band 
has  been  properly  formed  and  not  distorted  afterwards, 
these  three  lines  will  intersect  in  a  point;  practically  they 


LOCALIZATIOX 


239 


are  likely  to  form  a  small  triangle,  but  with  an  excellent 
chance  of  the  projectile  being  located  in  this  small  area. 
If  one  now  identifies  the  cliagTam,  so  formed,  with  a  cross 
section  anatomy  for  the  same  region  of  the  body,  definite 
anatomical  inlormation  as  to  the  position  of  the  projec- 
tile and  the  relative  position  of  muscles  or  organs  likeh^ 
to  be  encountered  in  its  removal  is  gained. 

It  is  also  possible  to  use  two  short  bands  at  right  angles 

Meial  Strop^ 


Hinge  of  Mehl  Sfra^ 
Fig.  110,     Principle  of  profondometer  strip. 


to  each  other,  that  may  be  made  to  conform  to  the  body  at 
a  desired  point,  and  to  mount  an  indicating  rod  for  use 
during  operation. 

The  value  of  this  method  will  depend  to  a  considerable 
extent  upon  the  care  exercised  in  forming  and  handling 
the  strip  and  in  properly  adjusting  it  to  the  cross  section 
anatomy.  It  is  suggested  that  in  many  cases  at  least  one 
of  the  skin  marks  might  well  have  definite  relation  to  some 
anatomical  landmark,  so  that  there  could  be  little  opportu- 
nity for  a  rotation  of  the  band  with  reference  to  the  ana- 
tomical chart.     This  will  be  especially  true  of  portions 


240  U.  S.  ARMY  X-RAY  MANUAL 

where  the  cross  section  is  nearly  a  circle.  It  should  also 
be  observed  that  the  accuracy  of  this  method  increases  when 
the  three  sight  lines  are  made  to  differ  materially  in  di- 
rection. In  some  cases  this  would  be  a  difficult  matter,  as 
in  the  case  of  a  seriously  wounded  patient,  or  one  for  whom 
change  of  position  on  the  x-ray  table  is  painful. 

It  is  advised  in  every  case  that  three  lines  of  sight  be 
determined,  marking  six  skin  points,  and  for  this  purpose 
the  parallax  localizer  furnished  in  the  army  outfit  will  be 
found  very  valuable,  as  it  permits  of  marking  the  skin  on 
the  under  side  with  the  same  degree  of  certainty  as  on 
top.  It  may  be  noted  also  that  the  method  here  described 
eliminates  the  necessity  of  using  more  than  one  distinctive 
skin  mark,  and  it  would  do  no  harm,  when  using  this 
method  with  a  parallax  localizer  as  a  marking  device,  if 
at  least  one  depth  were  determined  as  a  check  upon  the 
accuracy  of  adjustment  of  the  profondometer  band. 

Those  who  are  especially  interested  will  find  articles  by 
Major  Flint  giving  more  details  with  reference  to  this 
method  in  The  Military  Surgeon  of  March,  1917,  and  the 
Annals  of  Surgery  for  August,  1917. 

Specific  Instructions  for  Method  D. — It  would  be 
rather  difficult  to  give  definite  directions  for  the  use  of  the 
profondometer,  because  no  explicit  measurements  are  made 
by  the  roentgenologist.  It  will,  perhaps,  suffice  to  point 
out  wherein  difficulties  or  inaccuracies  are  likely  to  result. 

1.  It  should  be  mentioned  that  the  six  points  represent- 
ing the  entrance  and  emergence  points  of  the  x-ray  beams 
used,  should,  if  possible,  be  well  spaced  round  the  body; 
in  other  words  the  angles  between  the  diametral  lines 
should  be  as  large  as  possible. 

2.  Great  care  must  be  taken  in  the  matter  of  forming  the 
metallic  strip  to  fit  the  body  in  the  plane  of  the  skin  marks 
and  to  insure  that  it  is  removed  without  distortion.    If  time 


LOCALIZATION  241 

permits  it  ini<2:lit  be  wise  to  check  by  a  second  attempt. 

3.  Care  should  be  taken  to  properly  orient  the  diagram 
secured  in  this  way  with  the  cross  section  anatomy  chart 
and,  to  facilitate  this,  it  might  be  well  to  identify  one  of 
the  skin  points  with  reference  to  the  immediately  under- 
lying anatomy. 

Method  E. — There  have  been  devised  both  before  and 
during  the  war  a  very  considerable  number  of  mechanical 
indicators  or  compasses  to  be  used  during  the  operation  as 
a  surgical  guide  to  better  utilize  information  acquired  by 
the  x-ra}^  examination.  Of  these,  the  one  devised  by  Dr. 
Hirtz  of  the  French  Roentgenological  Service  has  been  most 
generalh'  approved  by  roentgenologists  and  surgeons. 

As  originally  proposed,  this  instrument  was  intended 
to  be  used  in  connection  with  radiographic  work,  whereby 
a  permanent  record  could  be  made  for  the  later  setting 
of  the  compass,  provided  the  identifying  skin  marks  were 
not  obliterated.  On  account  of  the  very  considerable  time 
necessary  to  prepare  a  negative  for  examination  and  meas- 
urement, it  has  been  found  desirable  in  many  cases  to 
operate  the  compass  by  data  secured  from  fluoroscopic  ex- 
amination, which  is  much  more  expeditious  and,  in  many 
cases,  will  serve  fully  as  well. 

The  essential  feature  of  the  Hirtz  compass  is  the  pos- 
sibility of  adjustment  of  the  movable  legs  that  support  the 
instrument,  so  that  when  resting  on  fixed  marks  on  the 
body  of  the  patient  the  foreign  body  will  be  at  the  center 
of  a  sphere,  a  meridian  arc  of  which  is  carried  by  the  com- 
pass. This  arc  is  capable  of  adjustment  in  any  position 
about  a  central  axis.  An  indicating  rod  passes  through  a 
slider  attached  to  the  movable  arc  in  such  a  way  as  to  co- 
incide in  all  positions  with  a  radius  of  the  sphere,  and 
whether  it  actually  reaches  the  center  or  not  it  is  always 
directed  toward  that  point.    If  its  movement  to  the  center 


242 


U.  S.  AR.AIY  X-RAY  :\rAXrAL 


of  the  sphere  is  obstructed  by  tlie  body  of  the  patient,  the 
amount  it  lacks  of  reaching  the  center  will  be  tlie  depth  of 
the  projectile  in  the  direction  indicated  by  the  pointer. 

The  value  of  the  compass  lies  in  its  wide  possibility  as 
a  surgical  guide,  in  that  it  does  not  confine  the  attention 


Fig.  111.     Hirtz  compass. 

of  the  surgeon  to  a  single  point  marked  on  the  skin,  with  a 
possible  uncertainty  as  to  the  direction  in  which  he  should 
proceed  in  order  to  reach  the  projectile,  but  gives  him  a 
wide  latitude  of  approach  and  explicit  information  as  to 
depth  in  a  direction  of  his  own  selection. 

The  compass  is  shown  in  Fig.  Ill  and  schematically  in 
Fig.  112.  Three  metal  arms  respectively  labeled  1,  2,  and 
3  in  clockwise  rotation  are  so  mounted  as  to  turn  freely 


LOCALIZATION 


243 


upon  a  central  pivot  and  have  their  upper  surfaces  all  in 
a  single  plane.  Each  of  these  arms  carries  a  slider,  whicli 
may  be  adjusted  to  any  position  along  tlie  length  of  the 
arm.  Each  slider  has  an  adjustable  leg  at  right  angles  to 
the  plane  of  the  arms,  that  may  be  held  in  any  position  by 
a  small  thumb  screw.  These  legs  are  graduated  and  the 
zero  point  is  not  at  either  end  of  the  legs,  but  a  few  centi- 
meters below  the  upper  portion,  which  terminates  in  a 
small  knob.     The   center  post  about  which  the   arms  ro- 


FiG.  112.  Schematic  drawing  of  Hirtz  compass  with  legs  adjusted 
at  zero  points  and  resting  on  a  plane. 

tate  has  a  hole  at  right  angles  to  the  plane  of  the  arms 
and  is  also  shaped  to  carry  the  curved  metal  arc,  A  (Fig. 
112).  The  hole  in  the  slider  on  arc,  A,  carrying  the  indi- 
cating rod,  can  be  made  to  coincide  with  the  opening 
through  the  center  post. 

ATlien  the  three  legs  are  set  at  zero,  ciuite  irrespective  of 
the  position  of  the  slider  on  the  arms  or  of  their  angular 
position,  and  the  compass  stands  on  a  plane  surface,  the  in- 
dicating rod,  passed  through  the  slider  on  arc.  A,  will 
touch  the  supporting  plane  at  the  center  of  the  sphere  of 
which  A  is  a  meridian  arc.  A  friction  clip  on  the  indicat- 
ing rod  may  be  adjusted  in  contact  with  the  slider  on  A, 


244 


U.  S.  ARMY  X-RAY  ]\rANTIAL 


and  the  distance  from  the  lower  end  of  this  clip  to  the 
pointed  end  of  the  indicator  will  be  the  radius  of  the 
sphere  of  which  A  is  an  arc. 

Fig.  113  shows  the  compass  with  the  legs  shifted  so 
that  they  no  longer  stand  on  the  base  plane,  and,  in  fact, 
are  at  quite  different  heights;  but  the  arc,  A,  and  the  arms 
of  the  compass  have  not  heen  displaced,  so  that  the  pointer 
still  reaches  the  center  point,  P,  in  this  plane. 

Fig.  114  shows  the  compass  actually  set  upon  the  body  of 


Fig.  113.  Arms  and  indicator  of  Hirtz  compass.  Same  position 
as  in  Fig.  112,  but  with  legs  elevated  on  blocks  whose  tops  might 
correspond  to   skin  markers. 


a  patient,  its  legs  resting  on  three  skin  marks,  M,  N,  and 
Oj  and  with  the  indicating  rod  pointing  toward  the  pro- 
jectile, but  failing  to  reach,  it  because  of  contact  with  the 
skin  of  the  patient  at  ^S'.  The  depth,  of  the  projectile  in 
this  particular  direction  is  indicated  in  Fig.  114  by  d. 
If,  now,  the  indicating  rod  is  placed  in  the  slider  carried 
by  the  arc,  A,  the  rod  touches  the  skin  at  a  different  point, 
8%  and  the  distance  between  the  friction  clamp  on  the 
rod  and  the  upper  surface  of  the  slider  on  the  arc,  A,  will 
be  the  depth  of  the  foreign  body  along  the  direction  indi- 
cated by  the  dotted  line.    It  is  evident  from  the  construe- 


LOCALIZATION 


245 


tion  that  the  surgeon  may  place  the  arc,  A,  in  any  po- 
sition throughout  :3()()°,  and  the  slider  at  any  position  from 
the  center  to  the  extreme  end  of  the  arc,  and  still  have 
the  indicating  rod  i)oint  to  the  foreign  hody  and  show  its 
depth  from  the  point  of  contact  with  the  skin.  Fig.  115 
shows  the  compass  in  position  on  the  patient  at  operation. 
The  exact  amount  which  each  leg  of  the  compass  must  be 
shifted  from  its  zero  point  in  order  to  stand  on  the  marker 


Fig.  114.     Schematic  drawing  of  Hirtz  compass  set  up  on  skin  of 
patient. 


to  which  it  belongs  and  yet  have  the  indicating  rod  in  the 
proper  position  is  easiest  seen  in  Fig.  116,  in  which  only 
a  single  leg  of  the  compass  is  shown ;  but  the  same  will 
apply  to  each  of  the  legs  in  turn.  Imagine  a  plane,  paral- 
lel to  the  plane  of  the  three  arms  of  the  compass,  to  be 
drawn  through  the  projectile.  The  leg  attached  at  arm 
number  one,  standing  on  the  marker,  M,  would,  if  it  could 
pass  down  to  this  plane,  intersect  the  plane  at  the  point, 
E,  and,  under  these  circumstances,  the  indicator  passing 
through  the  central  post  of  the  instrument  would  touch  the 
skin  at  S,  vertically  above  P.     If  the  distance  from  the 


246 


U.  S.  AR]\IY  X-RAY  IMANUAL 


plane,  from  which  measurements  are  made,  to  the  lower 
plane,  containing  the  projectile,  is  measured  and,  like- 
wise, the  distance  J/J/',  it  is  seen  that  the  amount  by 
which  this  particular  leg  is  raised  from  its  zero  point, 
where  it  would  be  set  if  it  reached  the  point,  E,  will  be 
the  difference  between  the  depth  of  the  foreign  body  and 


Fig.  115.     Hirtz  compass  in  position. 


the  depth  of  the  marker  from  any  plane  of  measurement, 
for  example,  that  of  the  fluoroscopic  screen  or  a  photo- 
graphic plate.  The  fluoroscopic  screen  may  be  placed  in 
any  position  parallel  to  the  base  plane,  EP,  and  the  differ- 
ence, ME,  would  be  quite  independent  of  the  height  of  the 
plane  from  which  all  measurements  are  made. 

This  may  be  summarized  by  saying  that  each  rod  is  to 
be  shifted  from  its  zero  point  an  amount  equal  to  the  dif- 
ference between  the  depth  of  the  projectile  below  the  flu- 


LOCALIZxVTIOX 


247 


oroscopic  screen,  or  other  plane  of  reference,  and  the  depth 
of  the  skin  mark  upon  which  this  particular  leg  would 
stand,  measured  from  the  same  plane.  It  is  absolutely 
essential  in  the  use  of  the  compass  to  adopt  a  systematic 
procedure,  so  that  the  arm  to  carry  the  leg  is  identified 
with  the  depth  measurement  of  its  own  skin  point. 

The  data  necessary  to  properly  adjust  the  compass  may 
now  be  stated  by  reference  to  Figs.  112  and  116.  The 
indicating  rod  in  the  central  position  and  the  three  legs 


Fig.  116.     Eeason  for  shift  of  leg  of  compass  from  zero  point  by 
the  amount  stated. 


of  the  compass  mark  out,  in  any  plane  parallel  to  the  base 
plane  of  Fig.  112,  four  points  of  definite  position  in  the 
plane.  Any  vertical  shift  of  the  legs  will  still  allow  them 
to  retain  their  position  in  lines  passing  through  the  points, 
E,  F,  G  and  P.  The  point  G,  Fig.  112,  is  then  in  a  ver- 
tical line  passing  through  the  marker,  M,  and  the  data 
necessary  to  set  the  compass  must  give  the  position  in  a 
plane  of  these  four  points  and,  in  addition  to  this,  must 
give  the  depth  from  a  fixed  plane,  parallel  to  the  base  plane, 
EFG,  of  the  three  markers  on  the  skin  of  the  patient  and 
of  the  projectile  within  the  patient's  body.  Whether  this 
data  is  to  be  found  by  a  photographic  or  a  fluoroscopic 


248 


U.  S.  AR]\rY  X-RAY  MANUAL 


process  is  immaterial,  as  the  steps  in  its  use  will  be  iden- 
tical. 

When  a  fluoroscopic  method  is  to  be  used,  an  auxiliary 
device  may  be  found  of  considerable  aid  in  rapidly  and 
accurately  securing  the  requisite  data.     Such  a  device  is 


> 

^ 

l\ 

Fig.  117.  Accessory  apparatus  for  fluoroscopic  work  with  Hirtz 
compass. 

(a)  Auxiliary  compass,  pedestal  support  and  three  markers  with 
friction  clips. 

(b)  Hirtz  compass  mounted  with  the  three  legs  at  different  levels, 
so  that  a  pointer  reaches  white  spot  on  the  base  plane  at  the  center 
of  the  sphere  of  which  the  curved  arc  is  a  part. 

shown  at  A,  Fig.  117,  and  consists  of  three  arms,  each 
with  a  slider  very  similar  to  the  original  compass.  In  fact 
the  latter  may  be  used  with  rather  less  convenience,  by  re- 
moving arc.  A,  and  allowing  the  indicating  rod  to  project 
a  short  distance  below  the  center,  with  the  legs  tempora- 
rily removed.     The  auxiliary  compass  has  its  arms  num- 


LOCALIZATION  249 

bered  in  tlie  same  way  as  the  original  Ilirtz  compass  and 
has  a  projecting-  pin  which  fits  the  perforation  in  the 
screen.  One  of  the  arms  is  rigidly  attached  to  a  ring 
concentric  with  the  axis  of  rotation  about  the  pin,  while 
tl:e  other  two  are  movable,  but  may  be  clamped  by  thumb 
r.uts  to  the  ring.  It  is  evident  that  placing  the  perfora- 
tion in  the  screen  in  the  vertical  ray  passing  through  the 
projectile  definitel}^  fixes  the  position  of  the  center  jDost.  If, 
then,  each  marker  in  turn  is  brought  into  the  vertical  ray 
and  the  arm  and  slider  adjusted  so  that  the  hole  in  the 
slider  matches  such  a  projection  of  each  marker,  the  three 
openings  in  the  sliders  and  the  central  pin  fix  the  four 
points  which  it  is  necessary  to  obtain.  It  then  remains 
to  determine  the  depth  of  the  projectile,  for  which  one 
of  the  methods.  A,  B,  or  C  should  be  employed  and  also 
to  determine  the  distance  from  the  screen  to  the  opaque 
markers.  When  using  the  fluoroscopic  method,  the  latter 
depth  can  be  very  readily  determined  by  simply  passing 
a  suitable  measuring  rod  through  the  perforated  screen, 
which  has  been  brought  into  the  vertical  ray  passing 
througb  the  marker.  This  depth  is  to  be  recorded  and 
accurately  identified  with  the  arm  carrying  the  slider 
corresponding  to  that  particular  skin  marker.  In  order  to 
facilitate  this  measurement  a  set  of  three  measuring  rods 
with  friction  clips,  differing  slightly  in  shape,  are  pro- 
vided. As  soon  as  these  four  depths  and  the  four  marks 
in  the  plane  of  the  screen  have  been  determined,  the  work 
of  the  roentgenologist  is  completed,  provided  he  has  made 
sure  that  the  skin  marks  are  plainly  visible.  The  adjust- 
ment of  the  compass  may  then  be  carried  out  by  an  assist- 
ant to  either  the  roentgenologist  or  the  surgeon,  after  which 
the  instrument  can  be  sterilized  and  is  ready  for  the  sur- 
geon's use. 


250  U.  S.  AR:\rY  X-RAY  MANUAL 

Fluoroscopic  Method  With  Auxiliary  Compass — 

1.  Find  the  shadow  of  the  projectile,  Pq,  on  the  screen, 
and  reduce  the  size  of  the  diaphragm,  keeping  the  shadow 
in  the  center  of  the  illuminated  area. 

2.  Adjust  the  screen  so  that  the  opening  at  the  center 
of  the  screen  coincides  with  the  center  of  the  shadow ; 
lock  screen  carriage  in  this  position  for  all  except  vertical 
travel. 

3.  Mark  the  skin  through  the  opening  by  use  of  the 
special  marker  provided. 

4.  Determine  the  depth  of  the  projectile  by  either 
Method  A  or  C. 

5.  Raise  the  screen  and  attach  three  metallic  markers 
(preferably  three  small  w^ashers)  to  the  skin  at  suitable 
points,  and  mark  the  skin  at  each  point  selected.  Choose 
skin  points  with  care  to  ensure: 

a.  No  interference  with  probable  incision. 

b.  Proper  stability  of  the  compass. 

c.  As  firm  foot  points  as  possible. 

6.  Lower  the  screen  near  to  or  touching  the  skin,  with 
the  central  hole  still  in  the  vertical  ray  through  the  pro- 
jectile, and  insert  the  pin  of  the  auxiliary  compass  in 
the  hole.  Be  sure  that  the  screen  is  locked  in  position. 
Bring  arm  marked  1  to  point  toward  the  operator's  right 
and  loosen  thumb  nuts  on  arms  2  and  3. 

7.  Shift  the  tube  to  bring  the  right-hand  marker  in  the 
vertical  ray  (leaving  screen  locked),  and  adjust  the  slider 
on  arm  number  one  so  that  its  opening  coincides  with  the 
projection  of  the  marker,  Fig.  118.  If  washers  are  used 
the  round  opening  is  easily  identified. 

8.  Do  the  same  with  each  of  the  other  two  markers, 
ensuring  that  number  (1)  does  not  move  when  adjusting 
the  others  (a  small  clamp  Avill  aid  in  this)   and  lock  each 


LOCALIZATION 


251 


-*  ""i-     -*^ 


Fig.  11>'.     Method   of  using  fluoroscopic   adapter   -n-ith   Hirtz  com- 
pass. 

arm.     The  central  pin  and  the  three  sliders  then  give  the 
positions  for  the  arms  and  sliders  of  the  compass. 

9.     Kemove   the   auxiliary   compass   and   determine   the 


252  U.  S.  ARMY  X-RAY  MANUAL 

deptli  of  M,  N,  and  0  below  the  upper  surface  of  the  glass 
on  the  screen.  For  the  depths  of  31,  N,  and  0  use  the  small 
rods  provided  with  friction  sliders  and  make  the  measure- 
ment by  passing  the  rod  through  the  perforation  in  the 
screen,  which,  for  this  purpose,  is  to  be  brought  vertically 
over  each  marker  in  turn.  If  the  friction  clips  are  then 
pushed  down  until  they  touch  the  glass  and  are  properly 
adjusted  as  to  friction,  the  distance  from  the  clips  to  the 
end  of  the  rod  will  indicate  the  depth  desired.  These  slid- 
ing clips  are  shaped  to  correspond  to  the  projecting  blocks 
on  the  sliders  of  the  auxiliary  compass,  and  care  must  be 
taken  to  use  them  in  their  proper  places,  so  that  there  is  a 
complete  identification  of  the  compass  slider  and  the 
depth  of  the  marker  corresponding.  Form  the  habit  of 
using  these  in  a  definite  order,  during  these  depth  meas- 
urements, to  minimize  chances  of  error.  If  no  further 
fluoroscopic  work  is  to  be  done  these  depths  may  be  deter- 
mined in  daylight.  Otherwise  use  the  vertical  ray  from 
the  tube. 

Setting"  the  Hirtz  Compass — 
A.     By  Use  of  the  Auxiliary  Compass — ■ 

1.  Remove  the  arc  and  the  indicator  rod;  lower  the 
three  legs  until  the  upper  (rounded)  ends  project  one  to 
two  centimeters. 

2.  Lay  the  auxiliary  compass  on  a  flat  surface  with  the 
center  pin  upward.  Invert  the  Hirtz  compass  and  place 
the  central  hole  on  the  pin  of  the  auxiliary.  Unlock  wing- 
nut  at  center  of  compass,  thus  releasing  the  arms ;  bring 
arm  number  1  and  its  slider  to  such  a  position  that  on 
loosening  leg  number  1,  it  will  drop  into  hole  of  the  number 
1  slider  of  the  auxiliary.  Tighten  set  screws  of  slider  and 
of  leg  number  1.  Fig.  119.  Proceed  in  the  same  manner 
with  arms,  sliders  and  legs  numbers  2  and  3.  Tighten  wing- 
nut  at  center  of  Hirtz  compass,  thus  locking  compass  arms. 


LOCALIZATION 


253 


3.  If  pedestal  support  is  provided,  set  the  lock  sleeve 
on  the  vertical  rod,  so  that,  when  the  pedestal  stands  on 
a  flat  surface,  and  the  Ilirtz  compass  is  placed  thereon, 


Fig.  119.     letting  arms  and  legs  of  Hirtz  compass  directly  from 
the  auxiliary  compass. 


with  the  pedestal  rod  through  the  central  hole  of  the 
compass,  it  will  be  supported  in  such  a  position  that  the 
legs  will  drop  to  their  zero  points  when  loosened,  leaving 
the  compass  supported  on  the  pedestal. 

4.     Shift  each  leg  an  amount  equal  to  the  difference  be- 


254  U.  S.  ARMY  X-RAY  MANUAL 

tween  the  depth  of  the  projectile  and  the  depth  of  the 
skm  marker  on  which  each  individual  leg  is  to  stand.  (Leg 
number  1  stands  on  skin  marker  number  1,  etc.)  Tighten 
each  leg,  replace  compass  arc  and  indicating  rod,  the 
latter  with  lock  sleeve  properly  set,  and  the  compass  is 
ready  for  sterilization  and  use  by  the  surgeon. 

Note. — This  subtraction  can  conveniently  be  made  by 
laying  off  on  paper  the  distance  from  the  top  of  the  lead 
glass  on  the  screen  to  P,  then,  placing  auxiliary  rod  num- 
ber 1  with  its  sleeve  indicating  the  skin  depth  for  marker 
one,  mark  this  distance  on  the  line  previously  made,  and 
reset  the  sleeve  to  the  length  remaining  on  the  projectile 
depth  line. 

It  is  recommended  that  even  if  the  compass  is  to  be 
immediately  set  direct  from  the  auxiliary  a  record  of  the 
data  necessary  for  setting  be  made  and  retained  until  after 
the  operation. 
B.     From  the  Diagram  of  Data — 

1.  The  auxiliary,  having  been  set  to  mark  shadows  on 
the  screen,  is  placed  on  a  plain  sheet  of  paper  with  center 
pin  down.  Indicate  with  a  pen  the  spot  on  the  paper 
where  the  pin  touches  and  mark  it  Pq  (being  directly  over 
the  projectile) — a  small  drawing  board  with  a  hole  in  the 
center,  in  which  the  pin  may  be  inserted  through  the  record 
paper,  may  be  helpful.  Indicate  the  locations  of  the  holes 
in  sliders  1,  2,  and  3,  thus  giving  their  relations  to  Pq/ 
identify  each  by  number  and  write  opposite  each  the  depth 
in  centimeters  to  the  skin  below  the  fluoroscopic  screen. 
The  depth  of  Pq  below  screen  must  be  similarly  indicated. 

2.  Take  the  Hirtz  compass  with  indicating  rod  inserted 
in  central  hole,  and  set  point  of  indicating  rod  on  Pq  of 
diagram.  Loosen  wing-nut  at  compass  center,  thus  releas- 
ing arms;  bring  leg  number  1  to  stand  on  mark  number  1 
of  diagram.    Proceed  identically  with  legs  numbers  2  and 


LOCALIZATION  255 

3;  then,  with  indicating  rod  and  the  three  legs  accurately 
on  the  proper  points  of  diagram,  tighten  wing-nut  to  lock 
compass.     Tighten  all  set  screws. 

3.  Place  the  compass  on  pedestal  support  and  proceed 
as  indicated  in  paragraph  4  above. 

The  instrument  is  now  ready  for  sterilization  and  use 
by  the  surgeon.  Care  must  be  taken  to  avoid  handling 
the  compass  in  any  manner  that  would  displace  any  of  the 
settings.  In  case  of  deferred  operation,  the  four  skin 
marks  should  be  tattooed,  or  they  must  be  renewed  with 
sufficient  frequency  to  insure  their  identification  at  time 
of  operation.     If  metal  washers   are  used,   they  may  be 

A  ^ 


c 

r 


:!ifSlsSii!i^>!^SSiSSiSiiiSSS^i)i^^ 


Fig.  120.     Detail  of  holder  for  direct  setting  of  Hirtz  compass. 

sterilized  and  attached  at  the  time  of  the  operation;  they 
serve  very  well  to  hold  the  compass  legs  on  their  proper 
skin  points. 

Direct  Setting  of  the  Hirtz  Compass. — Several  devices 
for  holding  the  Hirtz  compass  in  order  to  make  a  direct 
adjustment  of  the  foot  points  and  leg  heights  on  the  pa- 
tient have  been  proposed.  This  method  possesses  two  dis- 
tinct advantages:  (1)  it  may  be  done  quite  expeditiously; 
(2)  it  indicates  clearly  to  the  operator  how  the  compass 
is  going  to  stand  on  the  patient  when  in  use.  Its  dis- 
advantages are:  (1)  the  necessity  of  considerable  illumi- 
nation in  the  fluoroscopic  room  when  placing  the  compass ; 
(2)  danger  of  movement  of  the  patient  between  localiza- 
tion and  final  adjustment;  (3)  need  for  the  compass  both 
in  the  fluoroscopic  room  and  in  the  operating  room. 


256  U.  S.  ARMY  X-RAY  MANUAL 

In  order  to  adapt  this  method  to  the  standard  table,  the 
design  shown  in  Fig.  120  has  been  developed.  This  con- 
sists of  a  tube  fitting  into  the  socket  of  the  screen  carrier, 
holding  a  square  sliding  rod  with  an  end  socket  taking 
the  hub  of  the  compass. 

The  collar.  A,  on  the  tube  has  a  V-shaped  projection  in- 
tended to  fit  a  notch  in  the  carrier  socket  so  as  to  prevent 
rotation  from  a  definitely  determined  position. 

The  fundamental  principles  in  this  method  are  the  align- 
ment of  the  central  axis  of  the  compass  with  the  vertical 
ray  through  the  projectile,  and  the  bringing  of  the  com- 
pass to  the  proper  height  so  that  the  top  of  the  slider  on 
the  arc,  when  in  its  central  position,  is  at  a  distance  from 
the  projectile  equal  to  the  radius  of  the  arc. 

In  order  to  secure  the  former,  the  holder  should  enable 
us  to  readily  make  the  plane  of  the  arms  level.  Then,  the 
compass  should  be  allowed  to  move  up  or  down  in  a  vertical 
direction  without  rotation.  "When  the  indicator  is  placed 
in  the  central  position  and  the  compass  is  properly  placed 
on  the  patient,  the  radius  mark  on  the  pointer  will  be  as 
far  above  the  arc  slider,  through  which  the  pointer  is 
inserted,  as  the  measured  depth  of  the  projectile  along 
the  vertical  ray.  While  rigidly  held  in  this  position  the 
arms  and  legs  may  be  adjusted  at  will  to  support  the 
compass  in  this  position.  Fig.  121. 

Care  must  be  taken  to  ensure : 

1.  That  the  patient  does  not  move  between  the  locali- 
zation and  the  completion  of  the  adjustment. 

2.  That  the  pointer  is  raised  from  its  zero  the  correct 
distance. 

3.  That  all  parts  of  the  compass  are  locked  before  re- 
moval from  the  body. 

The  holder  must  be  adjusted  before  it  is  used  the  first 
time  as  follows : 


LOCALIZATION 


257 


I 

p 

i 

lini 

Fig.  121.     Direct  setting  of  Hirtz  compass.     Compass  and  holder 
in  position. 


1.  Remove  screen-holding  rod  from  the  horizontal  socket 
and  insert  holder. 

2.  Remove  arc  from  the   compass,   insert  hub  in  the 


258  U.  S.  ARMY  X-RAY  :\rANUAL 

holder,  and  place  two  of  the  arms  close  together  so  that 
the  line  of  the  holder  bisects  the  angle  between  them. 
Then  lock  the  center  arm  clamp. 

3.  riace  a  small  level  on  the  two  arms  perpendicular 
to  the  holder  rod,  and  rotate  rod  until  this  shows  level, 
then  clamp  by  socket  set-screws. 

4.  ]\Iake  a  scratch  mark  where  the  ''Y"  on  the  ring 
comes  in  contact  with  the  socket. 

5.  Remove  the  holder  and  file  a  small  notch  with  a 
triangular  file  to  take  the  ''Y"  on  the  collar. 

6.  Test  out  as  to  level,  when  the  holder  is  replaced  in 
the  socket  with  the  ''Y"  engaging  the  notch.  If  not 
quite  correct,  loosen  the  set  screws  at  the  end  where  the 
square  rod  enters,  rotate  to  level,  and  fasten  firmly. 

The  above  needs  to  be  done  only  once  and  the  procedure 
for  use  is  then  quite  simple. 

1.  Remove  arc  from  the  compass  and  insert  in  the 
holder,  fastening  with  the  thumb  nut,  B. 

2.  Set  the  sliding  clamp  on  the  indicator  rod  at  the 
ring  mark,  i.  e.,  so  that  the  distance  from  the  lower  end 
of  the  slider  to  the  pointed  end  of  the  indicator  is  the 
radius  of  the  arc. 

3.  Insert  indicator  in  the  compass  holder  and  raise  until 
the  distance  from  the  top  of  the  brass  holder  to  the  lower 
end  of  the  sliding  clamp  is  the  projectile  depth  below  the 
skin  mark.     Fasten  by  nut,  C. 

4.  Raise  the  legs  of  the  compass  and  adjust  the  holder 
until  the  lower  end  of  the  pointer  rests  on  the  skin  mark. 
Lock  carrier  in  position. 

5.  Place  arms  and  feet  as  desired  so  that  the  latter 
rest  on  as  firm  skin  points  as  possible,  and  clamp  all  parts 
of  the  compass. 

6.  Raise  compass  slightly  by  the  vertical  movement  of 
the  carrier,  mark  skin  points  for  the  feet,  and  identify  them 


LOCALIZATION 


259 


Fig.  122.     Centering  of  tube  above  plate  holder  on  cassette  with 
small  cross  wires,  photographic  method,  Hirtz  compass. 


260  U.  S.  ARMY  X-RAY  IMANUAL 

clearly.  This  method  is  much  more  convenient  than  to 
mark  the  skin  first  and  then  adjust  the  compass  to  fit 
the  marks. 


Fig.  123.  Skin  markers,  plate  holder  and  tube  holder  in  position 
for  photographic  method,  Hirtz  compass. 

7.  Remove  compass,  read  and  record  height  settings  of 
legs,  then  record  position  of  foot  points,  and  center  for 
resetting  the  compass  later  if  it  should  be  necessary. 


LOCALIZATION  261 

8.  For  use  in  the  operating  room  the  compass  may  be 
sterilized  by  a  flame. 

Use  of  the  Hirtz  Compass  with  Plates. — AVhen  it  is  de- 
sired  to  establish  the  data  necessary  for  the  use  of  the 
compass  with  photographic  plates  or  films,  it  is  necessary 
that  two  exposures  be  made  from  two  different  target  posi- 
tions, either  upon  a  single  plate,  or  upon  two  separate 
plates  or  Alms,  without  movement  of  the  patient  or  skin 
markers.    The  latter  method  is  usually  preferred. 

There  is  furnished  for  this  w^ork  a  small,  flat  square  of 
celluloid  into  w^hich  are  inserted  two  small  steel  wires  form- 
ing a  right-angled  cross.  The  celluloid  has  tw^o  holes 
punched  in  diagonally  opposite  corners,  through  which  a 
tape  may  be  passed,  and  this  is  to  be  tied  around  the  tun- 
nel plate  changer  so  as  to  fix  the  desired  centering  mark, 
when  two  plates  or  two  films  are  to  be  used. 

Fig.  122  shows  how^  the  tube  is  centered,  using  a  plumb 
line  to  secure  exact  position.  This  must  be  done  before 
the  patient  is  placed  in  position;  and  care  must  be  taken 
not  to  disturb  the  adjustment. 

Fig.  123  shows  the  tube,  patient,  and  markers  in  po- 
sition for  one  of  these  exposures.  Do  not  forget  to  at- 
tach to  the  plate  tunnel  the  marking  device  or  to  use  the 
three  metallic  markers  in  contact  with  the  patient's  skin 
at  points  properly  chosen  and  marked  for  identification. 

The  principle  of  the  method  is  shown  in  Fig.  124'.  A 
small  marker,  X,  is  placed  approximately  at  the  center  of 
the  plate,  if  one  plate  is  to  be  used,  or  on  top  of  the  plate 
changing  tunnel,  if  two  plates  are  to  be  exposed.  Let  CX 
be  a  perpendicular  erected  to  the  plane  of  the  plate  at  the 
point  X  and  extending  upward  a  distance  of  60  centime- 
ters. Let  F^  Fo  be  positions  of  the  focus  in  a  line  parallel 
to  the  plane  of  the  plate  at  the  level  C,  and  assume  that 
CFi  and  CF2  are  each  three  centimeters  in  length.     Sup- 


262 


U.  S.  ARMY  X-RAY  MANUAL 


pose  that  M  is  one  of  the  markers  on  the  patient's  body. 
When  an  exposure  is  made  with  the  target  at  1\,  the 
shadow  of  M  will  fall  on  tlie  plate  at  M^  and,  when  an  ex- 
posure is  made  from  the  position  Fo,  the  corresponding 
shadow  will  be  M^.  Had  the  exposure  been  continuous 
during  the  motion  of  the  target  from  F^  to  F^,  there 
would  have  been  found  on  the  plate  a  straight  line  of  shad- 

fz         C    f^ 


<;? 


\  It 


!\ 


^  /  I 

/ } 


vi^-^-a^f; 


;^^Q.^.j^2CA7^Pl 


,  Megatm 


A//        Mz 


Fig.  124.  Schematic  representation  of  plate,  cross  wire  marker 
and  tube  focus  positions  for  radiographic  use  of  Hirtz  compass. 

Fig.  125.  Construction  for  finding  one  of  the  foot  points  M.  from 
the  shadows  of  a  corresponding  marker  as  shown  at  M-^  and  M^  and 
the  shadow  of  the  cross  marker,  X. 


ows  connecting  M^  and  M^.  If  we  drop  perpendiculars 
from  the  two  focal  positions  to  the  plane  of  the  plate,  in- 
tersecting it  at  the  points  F\  F\,  we  see  that  F\  F\ 
M^  is  a  plane  perpendicular  to  the  plate  and  passes  through 
M^,  and  the  trace  of  this  plane  upon  the  plate  is  F\  31^. 

In  the  same  way  a  plane  passed  through  F.,  F\  Mo  will 
be  perpendicular  to  the  plate  and  its  trace  will  be  F\  M^. 
It  follows  from  geometry  that  the  intersecting  line  of  these 
two  planes,  MM^,  will  be  a  line  passing  through  the  point 


LOCALIZATION  263 

31  and  perpendicular  to  the  plate.  Consequently  3/o  is  the 
foot  point  of  this  marker  on  the  plate  to  be  used  in  the 
compass  adjustment.  Also  the  lines  M^  31^,  F\  F\  and 
F^  F^  are  parallel. 

Fig.  125  shows  part  of  a  developed  negative  upon  which 
there  appears  a  shadow  at  M^,  a  shadow  at  J/2  and  a  single 
image  of  the  marker  on  the  plate — a  single  image,  since 
its  motion  is  zero  or  nearly  so.  the  marker  being  almost 
in  contact  with  the  plate  itself.  If  one  joins  il/j  and  3L^ 
by  a  straight  line  and  then  draws  through  the  center  of 
the  cross  a  line  parallel  to  31^  31^  and  measures  a  three 
centimeter  length  on  this  line  through  X  in  each  direction 
from  the  center  of  the  cross,  the  points  so  determined  will 
be  F\  and  F\  of  Fig.  124.  Cross  connection  between 
the  ends  of  these  lines,  that  is  F\  31^  and  F\  31^  then  defi- 
nitely locates  the  point  31  which  will  be  the  foot  point 
sought. 

The  length  of  the  line  31^  M^,  will  clearly  decrease  as  31 
is  placed  nearer  the  plate,  and  increase  as  it  is  raised.  For 
the  definite  60  centimeter  target-plate  distance  and  6  cen- 
timeter tube  shift  there  corresponds  one  height  3131^  for 
one  image  shift  31^  31 2.  These  relative  values  are  shown  in 
Table  I  in  which  all  measurements  are  given  in  centi- 
meters or  tenths  of  centimeters. 

Fig.  126  shows  a  full  construction  and  necessary  record 
derived  from  the  photographic  plate  used  in  setting  the 
compass.  This  data  is  used  exactly  as  was  that  derived 
from  fluoroscopic  examination. 

It  will  require  a  considerable  amount  of  skill  and  judg- 
ment to  so  place  the  markers  on  the  patient's  skin  as  to 
give  reliable  readings  and  at  the  same  time  furnish  proper 
support  for  the  compass  when  used  at  operation.  Espe- 
cially one  must  insure  that  the  shadows  of  all  the  markers 
fall  on  the  photographic  plate.    It  is  also  clearly  undesir- 


264 


U.  S.  ARMY  X-RAY  MANUAL 


able  to  have  the  lines  whose  crossings  are  to  indicate  foot 
points  for  the  compass  setting  too  nearly  parallel,  as  in 
that  case  a  slight  error  in  their  location  may  bring  a  de- 
cidedly large  shift  in  the  position  of  foot  points.  Trans- 
parent celluloid  scales  are  sometimes  furnished,  which 
assist  somewhat  in  determining  whether  the  shadow  of  the 
markers  will  fall  on  the  plate. 
Operation — 

1.     Knowing  approximately,  by  previous  fluoroscopic  or 
other   examination,   the   position   of  the   projectile   whose 


PLftTE 


Fig.  126.     Complete  chart  for  setting  feet  of  Hirtz  compass. 

localization  is  sought,  select  a  plate  changer  of  proper 
size,  attach  the  cross,  and  place  on  the  table  in  the  posi- 
tion in  which  it  is  to  be  used. 

2.  By  means  of  the  plumb  bob  furnished,  adjust  the 
tube  stand  so  that  the  central  position  of  the  target  shall  be 
vertically  over  the  metallic  cross,  and  be  sure  that  the 
distance  CX,  Fig.  124,  is  60  cm.  Adjust  stops  to  allow  the 
tube  to  move  3  cm.  in  each  direction  from  the  central 
point. 

3.  Place  the  patient  on  the  tunnel  plate  changer,  taking 


LOCALIZATION  265 

care  that  the  cross,  plate  changer,  and  tube  are  not  dis- 
placed in  the  process.  Or,  if  the  tube  holder  is  rotated, 
fix  stop  for  its  exact  return. 

4.  ]\Iake  sure  that  the  tube  is  three  centimeters  from 
its  center  point  and  insert  a  plate. 

5.  Place  the  three  skin  markers  in  the  desired  position. 
The  balls  as  furnished  with  the  apparatus  may  be  used, 
or  small  metallic  markers,  preferably  V-shaped,  may  be 
attached  to  the  patient's  skin  with  small  pieces  of  ad- 
hesive. 

6.  ]\Iake  the  exposure  needed. 

7.  Remove  the  first  plate,  shift  the  tube  and  make  the 
second  exposure.  Do  not  attempt  to  get  the  data  from 
the  plate  or  film  until  it  is  dry.  If  it  is  once  scratched 
or  smeared,  it  will  be  impossible  later  to  get  good  meas- 
urement. 

If  the  exposures  are  to  be  made  on  a  single  plate,  be  sure 
not  to  overexpose.  "WHien  using  two  plates,  the  image  of 
the  cross  is  used  to  superimpose  the  plates  and  to  transfer 
the  data  to  the  record  sheet. 

8.  Make  the  record  described  above,  locating  the  foot 
points  and  the  center  points. 

9.  Eead  J/^  M^,  A^  Ao,  0^  0,  and  Fi  P,  in  centimeters 
and  fractions,  enter  these  on  the  record  under  column 
marked  spread,  and  enter  under  height  the  corresponding 
number  in  the  table  on  page  266. 

Thus: 

Spread         Height  Shift 

M^   M^         1.5 12 6.6  Pi   P2— 3A   3^ 

Ai    A,         2.1 15.5 3.1  Pi    P.— Ai    A^ 

Oi    Ol        3.6 22.5 -3.9  P^    P^—O^    Oo_ 

Pi    P2         2.7 18.6 

The  equipment  supplied  for  use  in  Method  E  is  shown 
in  Fig.  127. 


266  U.  S.  ARMY  X-RAY  MANUAL 

Table 

Focus  Plate  Distance     60 
Tube  Shift  6^ 

Spreading      Height  Spreading       Height         Spreading       Height 


.1 

1.0 

1.75 

13.55 

3.4 

21.7 

.15 

1.45 

1.8 

13.85 

3.45 

21.9 

.2 

1.95 

1.85 

14.15 

3.5 

22.1 

.25 

2.4 

1.9 

14.45 

3.55 

22.3 

.3 

2.85 

1.95 

14.7 

3.6 

22.5 

.35 

3.3 

2.0 

15.0 

3.65 

22.7 

A 

3.75 

2.05 

15.3 

3.7 

22.9 

.45 

4.2 

2.1 

15.55 

3.75 

23.05 

,5 

4.6 

2.15 

15.85 

3.8 

23.25 

.55 

5.05 

2.2 

16.1 

3.85 

23.45 

.6 

5.45 

2.25 

16.35 

3.9 

23.65 

.65 

5.85 

2.3 

16.65 

3.95 

23.8 

.7 

6.25 

2.35 

16.9 

4.0 

24.0 

.75 

6.65 

2.4 

17.15 

4.05 

24.2 

.8 

7.05 

2.45 

17.4 

4.1 

24.35 

.85 

7.45 

2.5 

17.65 

4.15 

24.55 

.9 

7.85 

2.55 

17.9 

4.2 

24.7 

.9,5 

8.2 

2.6 

18.15 

4.25 

24.9 

1.0 

8.55 

2.65 

18.4 

4.3 

25.05 

1.05 

8.95 

2.7 

18.6 

4.35 

25.2 

1.1 

9.3 

2.75 

18.85 

4.4 

25.4 

1.15 

9.65 

2.8 

19.1 

4.45 

25.55 

1.2 

10.0 

2.85 

19.3 

4.5 

25.7 

1.25 

10.35 

2.9 

19.55 

4.55 

25.85 

1.3 

10.7 

2.95 

19.8 

4.6 

26.05 

1.35 

11.0 

3.0 

20.0 

4.65 

26.2 

1.4 

11.35 

3.05 

20.2 

4.7 

26.35 

1.45 

11.7 

3.1 

20.45 

4.75 

26.5 

1.5 

12.0 

3.15 

20.65 

4.8 

26.65 

1.55 

12.3 

3.2 

20.85 

4.85 

26.8 

1.6 

12.65 

3.25 

21.1 

4.9 

26.95 

1.65 

12.95 

3.3 

21.3 

4.95 

27.1 

1.7 

13.25 

3.35 

21.5 

5.0 

27.25 

LOCALIZATION 


267 


Method  F. — This  metliod  is  one  that  has  been  known 
under  various  designations  and  attributed  to  a  variety  of 
authors.  It  may  be  described  as  the  method  of  direct  ap- 
proach through  the  skin  and  tissue  to  the  foreign  body, 
under  fluoroscopic  guidance ;  or,  according  to  the  apparatus 
used,  as  the  method  of  caniuda  and  trochar.     While  the 


Fig.  127.     Equipment  supplied  for  use  Trith  Hirtz  compass. 


method  has  been  advocated  by  some  excellent  surgeons  and 
has  naturally  given  good  results  in  many  cases,  it  is  re- 
garded by  the  Service  as  the  least  desirable  of  the  methods 
adopted  and  it  is  urgently  advised  that  it  should  never  be 
used  excepting  in  the  hands  of  an  operator  who  will  either 
work  under  the  direct  supervision  of  a  competent  surgeon 
or  anatomist,  or  who  has  acquired  that  degree  of  anatomi- 


268 


U.  S.  ARMY  X-RAY  MANUAL 


cal  knoAvledge  and  surgical  judo-ment  which  would  permit 
of  its  use  without  danger  to  the  patient. 

The  illustrations  in  various  publications  showing  the  in- 


;J 


Fig,  128.     Apparatus  for  Method  F. 


troduction  of  the  instruments  at  an  angle  with  the  line 
of  sight  should  be  completely  forgotten,  as  this  method  is 
bound  to  result  in  a  considerable  mutilation  of  the  tissue 
before  one  is  likely  to  come  in  contact  with  the  projectile. 


LOCALIZATION 


269 


Pig.  129.     Use  of  Method  F  with  a  perforated  screen. 


In  using  the  standard  army  outfit,  Fig.  128.  one  should 
bring  the  target  vertically  beneath  the  projectile,  stop 
down  the  diaphragm  to  a  moderate  size,  and  lock  the 
screen  against  all  excepting  vertical  motion,  with  the'cen- 


270  U.  S.  ARMY  X-RAY  MANUAL 

tral  perforation  in  the  vertical  ray  passing  through  the 
projectile.  Then  insert  the  cannula  and  trochar  through 
the  perforation  in  the  screen  and,  after  puncturing  the 
skin  with  the  sharp  pointed  instrument,  replace  this  by 
the  obturator  and  press  slowly  and  carefully  down  in  a 
strictly  vertical  direction,  until  either  contact  with  the 
projectile  is  felt  or  vision  at  two  slight  angles  indicates  that 
contact  has  been  made,  Fig.  129.  After  this,  remove  the 
trochar  and  pass  the  hooked  piano  wire  or  harpoon  through 
the  cannula,  being  sure  that  it  passes  beyond  the  end  of 
the  tube  and  that  it  is  not  withdrawn  on  removal  of  the 
cannula.  While  inserting  the  cannula  it  will  best  be  held 
by  use  of  a  strong  pair  of  forceps.  These  may  lie  flat 
upon  the  fluoroscopic  screen  and,  in  this  way,  the  keeping 
of  the  cannula  in  a  vertical  position  will  be  somewhat  easier. 
The  wire  which  has  been  inserted  may,  if  one  desires,  be  cut 
off  a  short  distance,  14  inch,  above  the  skin,  or  it  may  be 
bent  down  close  to  the  skin  and,  knowing  the  length  of  the 
original  wire,  the  amount  projecting  gives  the  surgeon  a 
definite  idea  of  depth. 

In  the  case  of  this  method  of  localization  but  little  in 
the  way  of  explicit  direction  can  be  given,  but  it  must 
be  understood  that  the  operator  should  know  the  line  of 
approach  with  reference  to  possibility  of  bony  obstruction 
and  of  dangerous  proximity  of  vital  organs,  before  he  un- 
dertakes the  work.  Also  he  should  invariably  work  with 
the  instrument  in  line  with  the  vertical  ray,  and  not  at- 
tempt to  insert  the  instrument  at  an  angle  with  this  line. 
Use  the  sharp  point  only  to  puncture  the  skin  and  replace 
immediately  by  the  obturator  or  blunt  point,  which  may  be 
inserted  with  far  less  danger  of  rupturing  the  blood  ves- 
sels. 


LOCALIZATION 


271 


272  U.  S.  ARMY  X-RAY  ]\IANUAL 

Fig.  130  shows  the  complete  set  of  accessories  for  locali- 
zation, as  supplied  and  grouped  according  to  the  designat- 
ing letters. 

Fluoroscopic  Assistance  During  Operation. — Several 
methods  have  been  proposed  for  the  utilization  of  the  fluor- 
oscope  at  the  time  of  operation,  especially  where  the 
mobility  of  the  projectile  in  the  tissue  and  the  uncertainty 
of  its  position  are  such  as  to  delay,  unduly,  the  work  of 
the  surgeon.  The  methods  so  far  proposed  may  be  grouped 
as  follows  under  four  heads: 

1.  The  x-ray  work  may  be  done  in  the  surgical  operat- 
ing room,  thus  requiring  the  surgeon  to  operate  in  special 
light,  which  mny  be  extinguished  when  he  desires  to  exam- 
ine fluoroscopically. 

2.  The  patient  may  be  returned  to  the  x-ray  room 
when  the  surgeon  requires  further  information. 

3.  The  roentgenologist  may  be  called  to  the  operating 
room  for  temporary  assistance  in  pointing  out  the  position 
of  the  projectile. 

4.  The  operation  may  be  performed  with  special  forceps 
while  using  the  fluoroscopic  light  as  a  guide. 

Each  of  these  propositions  has  its  own  difficulties  and 
merits.  The  objections  to  the  first  are  the  bad  fluoroscopic 
conditions  which  would  be  likely  to  prevail  and  the  fact  that 
the  x-ray  apparatus  would  be  operated  at  low  efficiency, 
being  necessarily  delayed  by  the  surgical  operation. 

In  the  second,  the  transfer  of  the  patient  back  to  the 
x-ray  room,  provided  a  suitable  stretcher  top  is  used,  may, 
of  course,  be  accomplished,  but  it  involves  moving  the  pa- 
tient back  again  for  operation  and  the  possible  displace- 
ment of  parts  during  the  transfer. 

The  objection  usually  raised  to  number  three  is  the  re- 
quirement of  x-ray  apparatus  in  the  operating  room  and 
the  possible  danger  from  sparks  igniting  an  ether-air  mix- 


LOCALIZATION 


273 


Fig.  131.     Intermittent   control.      Eoentgenologist   with   flu- 
oroseope  raised  ready  to  lower  it  and  proceed  with  examination. 


Fig.  132.     Intermittent     control.      Surgeon     and     roentgenologist 
"working  simultaneously. 


274  U.  S.  ARMY  X-RAY  IMANUAL 

ture.  The  latter  can  be  avoided  eitlier  by  making  the 
x-ray  apparatus  spark  proof  or  by  avoiding  tliese  fumes 
from  the  anesthetic  in  tlie  room.  The  roentgenologist 
must  be  supplied  with  a  bonnet  fluoroscope  which  auto- 
matically screens  the  eyes  by  suitably  colored  glasses  when 
he  seeks  to  find  his  way  about  a  lighted  room,  and  is  auto- 
matically lifted  or  removed,  when  the  fluoroscope  comes 
into  position. 

In  this  case  the  process  can  perhaps  be  illustrated  best 
by  Figs.  131  and  132,  showing  also  the  type  of  indicator 
used  by  the  roentgenologist  and  the  surgeon.  It  is  under- 
stood that  the  roentgenologist  working  above  the  sterile 
sheet  can  give  an  approximate  indication,  after  which  the 
surgeon,  using  a  sterile  pointer  below  the  sheet,  may, 
under  fluoroscopic  guidance  by  the  roentgenologist,  insert 
his  indicator  until  contact  is  attained,  after  which  the  op- 
eration may  proceed  as  before. 

The  fourth  method  is  essentially  one  for  the  expert  and 
will  probably  be  of  more  value  when  a  practical  stereoflu- 
oroscope  is  provided. 

The  following  extract  from  the  report  of  the  Senior  Con- 
sultant in  Roentgenology  of  the  American  Expeditionary 
Forces  in  France  indicates  the  preparation  which  will  be 
made  for  this  class  of  work. 

"The  ordinary  base  hospital  or  portable  table  regularly 
furnished  by  the  X-Ray  Division  of  the  Surgeon  General's 
Department  of  the  Army  will  serve  admirably  for  this 
type  of  surgery,  either  operating  with  the  bonnet  fluoro- 
scope in  the  usual  bright  light  of  the  operating  room,  or 
by  artificial  light  of  suitable  color  in  the  fluoroscopic  room 
of  the  x-ray  department,  with  proper  arrangements  for  con- 
veniently extinguishing  the  artificial  light  and  turning  on 
the  current  going  to  the  x-ray  tube.  An  order  has  been 
placed  for  a  hundred  extra  base  hospital  tables  without  the 


LOCALIZATION  275 

screen  support,  to  be  issued  to  operating  rooms  for  this 
very  purpose,  our  anticipation  being  that  the  bonnet  method 
will  be  far  more  popular  than  the  open  screen  method.  We 
have  acquired  in  France  a  small  supply  of  collapsible 
operating  tables  with  aluminum  tops,  also  designed  for 
this  special  type  of  radio-surgical  work.  Lacking  any  of 
these  tables,  the  roentgenologist  will  be  able  to  improvise 
a  suitable  equipment  by  combining  the  bedside  outfit  with 
an  ordinary  stretcher,  resting  on  the  regular  stretcher  sup- 
ports wdiich  will  be  available  in  the  field. 

"It  is  anticipated  that  the  usual  arrangement  will  be  a 
base  hospital  table  (without  screen  support)  with  over- 
head wire  connections  from  the  neighboring  x-ray  room, 
or  there  may  be  provided  a  special  bedside  unit  without  a 
tube  stand  with  the  tube  under  the  table. 

' '  For  operations  in  the  usual  light  of  the  operating  room, 
there  will  be  needed  a  bonnet  fluoroscope,  so  arranged  that 
when  the  roentgenologist  is  not  actually  working  with  the 
x-ray  his  accommodation  will  be  preserved  by  means  of 
dark  glasses,  automatically  dropped  before  his  eyes  when 
the  hood  of  the  bonnet  fluoroscope  is  turned  up ;  a  special 
metal  pointer  (mdicateur)  for  the  roentgenologist,  one  for 
the  surgeon;  and  a  forceps  for  projectile  extraction  of  spe- 
cial design  to  protect  the  hands  of  the  surgeon  from  the 
x-rays.  A  foot  switch  will  be  a  help,  but,  in  the  absence  of 
one,  an  assistant  can  turn  the  current  on  or  off  at  will. 
Both  hands  of  the  roentgenologist  must  be  free,  so  that 
he  may  be  able  to  work." 

The  following  paragraph  and  table  are  taken  from  an  ar- 
ticle by  J.  Metcalf  and  Keys-Wells  in  the  Lancet  of  May 
27,  1916. 

Depth  of  Anatomical  Landmarks  Beneath  the  Skin. — 
Surgeons  will  find  the  table  given  below  of  value  in  de- 
termining the  exact  position  of  a  foreign  body  in  relation 


276  U.  S.  ARMY  X-RAY  MANUAL 

to  points  on  the  skeleton.  In  their  article  published  in  con- 
nection with  this  table,  the  authors  state  that  the  surgeon 
often  experiences  many  difficulties  when  operating  for  the 
removal  of  a  foreign  body  even  after  the  roentgenologist 
has  made  an  accurate  localization.  Previous  to  the  war, 
the  surgeon  studied  the  ultimate  depth  of  his  operation 
only  with  regard  to  certain  surrounding  anatomical  land- 
marks, and  not  in  terms  of  centimeters  or  inches  beneath 
a  point  on  the  skin.  If  the  roentgenologist  reports  a 
projectile  as  being  4.5  cm.  from  a  point  on  the  skin  of 
the  back  overlying  the  transverse  process  of  the  12th  dorsal 
vertebra,  the  surgeon  has  little  knowledge  as  to  where  this 
depth  will  lead  him.  If,  however,  the  surgeon  knows  that 
the  average  depth  of  this  structure  is  less  than  4  cm.  from 
the  skin,  he  appreciates  the  fact  that  the  projectile  must 
lie  in  or  just  anterior  to  the  transverse  process.  The 
objection  is,  of  course,  that  individuals  vary  greatly  in 
thickness  of  various  parts,  but  the  authors  call  attention 
to  the  fact  that  the  soldier  is  selected  after  rigid  exam- 
ination and,  as  a  result,  the  extremely  thin  and  extremely 
obese  are  not  present. 

TABLE^ 

HEAD:     LATERALLY  DEPTH   OF   ANATOMICAL 

Incision  POSITION 

Just  above  zygoma  2.5  cm.  to  sphenosquamosal  suture 

Just  below  zygoma  4  cm.  to  sphenoidal  bone 

To  coronoid  process  or  condyle  of  mandible  2 . 5  cm. 

NECK:     ANTEROPOSTERIORLY 

Through  center  of  larynx  5  cm.  to  body  of  vertebra 

3  cm.  to  side  of  center  of  larynx  4  cm.    to     transverse     process     of 

cervical  vertebra 
3  cm.  to  side  of  center  of  larynx  7.5  cm.  total  depth  of  neck 

Through    middle   line    of   trachea   just   below 

cricoid  4  cm.  to  body  of  vertebra 

3  cm.  to  side  of  center  of  trachea  4  cm.  to  transverse  process  of  ver- 

tebra 
From  center  of  suprasternal  notch  3  cm.  to  posterior  border  of  manu- 

brium 

'Depths  were  given  in  inches  in  the  original  table,  but  have  here  been  converted  into 
centimeters. 


LOCALIZATION 


277 


NECK:  LATERALLY 


From  center  of  middle  of  neck. 

From  center  of  middle  of  neck. 

From  just  below  tip  of  mastoid  process 

CHEST:   SUPERIORLY 

From  a  point  midway  between  root  of  neck 
and  tip  of  acromion 

From  a  point  midway  between  internal  and 
external  extremities  and  just  behind 
posterior  border  of  the  clavicle 


DEPTH  OF  ANATOMICAL 
POSITION 
4  cm.     to     transverse     process     of 

vertebra 
6  cm.  to  body  of  vertebra 
6  cm.  to  body  of  1st  cervical 


5  cm.  to  apex  of  pleura,  downwards 
5  cm.  to  apex  of  pleura,  downwards 


CHEST:     ANTERIORLY 

From  center  of  lower  border  of  clavicle  back- 
wards to  subscapular  fossa  just  clear  of  ribs 

From  a  point  just  over  tip  of  coracoid  to  sub- 
scapular fossa  backwards 

From  a  point  2 . 5  cm.  external  to  sternoc4avi- 
cular  joint  just  below  clavicle 

From  a  point  2 . 5  cm.  external  to  sternoclavi- 
cular joint  just  below  clavicle 

From  a  point  5  cm.  external  to  sternoclavi- 
cular joint  just  below  clavicle  backwards_ 

From  a  point  5  cm.  external  to  sternoclavi- 
cular joint  just  below  clavicle  backwards 

From  a  point  5  cm.  below  center  of  clavicle 


7.5  cm. 
7.5  cm. 
3 . 5  cm.  to  1st  rib 

2  cm.  to  pleura 

3  cm.  to  1st  rib 

4  5  cm.  to  pleura 

5  cm.  to  pleura 


CHEST:     POSTERIORLY 

To  supraspinous  fossa 

To  intraspinous  fossa 

To  transverse  process  of  7th  cervical  vertebra 

To  pleura  level  of  7th  cervical  vertebra 

To  anterior  level  of  body  of  7th  cervical 

To  transverse  process  of  12th  dorsal  vertebra 

To  pleura  level  of  12th  dorsal  vertebra 

To  anterior  level  of  body  of  12th  dorsal  vertebra 


2.5  cm. 
2  cm. 

4  cm. 

5  cm. 
7.5  cm. 
3 . 5  cm. 
5  cm. 
8.5  cm. 


ABDOMEN:     THICKNESS  OF  WALL 
FROM   FRONT 

1  cm.  to  either  side  of  middle  line  just  above 

umbilicus  2.5  cm. 

1  cm.  to  either  side  of  middle  line  just  below 

umbilicus  3  cm. 

Just  internal  to  anterior  superior  spine  to  iliac 

fossa  7.5  cm. 

Midway  between  anterior  superior  spine  and 

pubic  crest  to  front  of  acetabulum  5  cm. 


ABDOMEN:     THICKNESS  OF  WALL 
FROM    SIDE 

On  level  of  tip  of  12th  rib  in  line  upwards  from 
anterior  superior  spine 


2 . 5  cm. 


ABDOMEN:     THICKNESS  OF  WALL 
FROM    BACK 

To  transverse  process  3d  lumbar  4 . 5  cm. 

To  anterior  level  of  body  of  3d  lumbar  11  cm. 

To  anterior  level  of  psoas  muscle  13  cm. 


278  U.  S.  ARMY  X-RAY  MANUAL 

HIP    AND    THIGH   FROM    FRONT  DEPTH  OF  ANATOMICAL 

POSITION 

8  cm.  below  anterior  superior  spine  to  head  of 

femur  G  cm. 

8  cm.  below  anterior  superior  spine  to  neok  of 

femur  5-7  cm. 

15  cm.   below   anterior   superior   spine    (level   of 

lesser  trochanter)  to  front  of  femur  4  cm. 

To  greater  trochanter  11  cm. 

To  lesser  trochanter  9  cm. 

Brim  of  pelvis  2 . 5  cm.    in  front  of  sacroiliac  syn- 
chondrosis 9 . 5  cm. 

To  anterior  inferior  spine  3  cm. 

To  spine  of  ischium  12.5 

To  ischial  tuberosity  13  cm. 

To  anterior  surface  of  line  of  junction  of 
ascending  ramus  of  ischium  and  descend- 
ing of  pubis  7  cm. 

HIP   AND   THIGH   FROM    BACK 

To  ischial  tuberosity  6  cm. 
To    spine    of    sacrum    on    level    of    posterior 

superior  spines  of  ilia  3  cm. 

To  sacral  groove  5  cm. 

To  head  of  femur  5  cm. 

To  greater  trochanter  9  cm. 

To  lesser  trochanter  _  7.5  cm. 

To  brim  of  pelvis  25  cm.  in  front  of  sacroiliac 

synchondrosis       _  10  cm. 

To  anterior  inferior  spine  15  cm. 

To  spine  of  ischium  5  cm. 
To  posterior  surface  of  junction  of  ascending 

ramus  of  ischium  and  descending  ramus  of 

pubis  11  cm. 


Eye  Localization. — In  the  case  of  foreign  bodies  in  the 
eye  very  accurate  localization  is  necessary,  as  knowledge 
of  the  exact  position  of  the  foreign  body  may  mean  the 
saving  of  an  eye  or  the  preservation  of  vision. 

The  simple  Sweet-Bowen  apparatus  consists  of  two  gen- 
eral parts :  the  base  or  head-rest,  as  illustrated  in  Fig.  133, 
and  the  localizer,  as  shown  in  outline  drawing,  Fig.  134. 

The  head-rest  base  is  composed  of  the  following 
parts : 

1.  A  plate-slide  tunnel,  so  constructed  as  to  protect 
one-half  of  a  5  x  7  photographic  plate  while  the  other  half 
is  being  exposed,  and  to  protect  the  exposed  half  while 
the  second  exposure  is  being  made. 

2.  Four  rubber-tipped  legs  to  raise  the  tunnel  so  that 


LOCALIZATION 


279 


it  will  act  as  a  pillow  to  hold  the  patient's  head  level 
when  lying  on  his  side. 

3.  A  plate-holder  having  a  slide  that  will  protect  the 
plate  from  the  ordinary  light,  but  offer  no  resistance  to 
the  x-ray. 


Fig.  133.    Head  rest  for  use  with  the  eye  localizer. 


4.  An  arm  or  handle  attached  to  the  plate-holding  slide 
to  enable  the  operator  to  shift  the  plate  the  correct  dis- 
tance for  each  exposure,  and  to  withdraw  the  same  when 
both  exposures  have  been  made. 

5.  A  pneumatic  cushion  for  the  comfort  of  the  patient. 

6.  A  double  clamp  to  hold  the  patient's  head  and  to 
prevent  any  horizontal  movement. 


280 


IJ.  S.  ARIMY  X-KAY  IMANUAL 


7.     A  single  vertical  clamp  to  press  the  head  downward 
upon  the  pneumatic  cushion. 
The  localizer  consists  of: 

1.  A  heavy  metal  base.  Fig.  134. 

2.  An  upright  standard,  B,  to  support  the  localizer  and 


^^^ 


,/* 


JfS    \        f/o 


B2 


Fig.  134.     Sweet  eye  localizer. 


permit  the  same  to  be  adjusted  and  held  firmly  at  any 
desired  height. 

3.  The  indicator-ball  D  with  its  needle-supporting  stem 
D^,  which,  when  properly  adjusted  to  the  center  of  an  eye, 
will  cast  its  shadow  on  the  photographic  plate  and  s^rve 
as  a  landmark  to  indicate  the  center  of  the  cornea. 

4.  The  metal  tip  E,  of  stem  E"^  is  made  cone-shaped, 
so  as  to  more  easily  differentiate  its  shadow  from  that  of 
ball   T>.     These   indicators   are   permanently   adjusted   a 


LOCALIZATION  281 

known  distance  apart  (15  millimeters),  and  the  base  of  the 
localizer  is  provided  with  two  holes  exactly  15  millimeters 
from  center  to  center,  which  should  be  employed  to  verify 
this  adjustment  in  case  of  doubt.  AVhen  an  x-ray  plate 
is  made  of  them  obliquely,  adjusted  to  an  eye  as  above 
stated  and  as  indicated  in  "front  view"  on  the  chart,  we 
are  enabled  by  their  shadows  to  definitely  locate  the  source 
and  course  of  the  rays  of  light  (in  relation  to  the  chart) 
that  caused  the  shadows.  Also,  the  position  of  any  foreign 
body  that  may  show  on  the  same  plate  can  very  easily  be 
determined  by  the  position  of  its  shadow  in  relation  to 
that  of  the  ball  and  cone,  because  the  exact  position  of 
the  latter  with  reference  to  the  chart  is  known  and  indi- 
cated (front  view). 

5.  Tube  C^^  and  notch  F'^^  are  sights  similar  to  those 
used  on  a  rifle,  with  which  the  operator  can  accurately 
align  the  center  of  the  cornea  of  the  afflicted  eye  with 
ball  D  and  its  supporting  step  Z)-.  F^^  is  a  spring  trig- 
ger which  presses  upwards  against  pin  F'^^.  F°  is  the  end 
of  the  rod  to  which  the  indicator-ball  and  cone  D  and  E 
are  attached  by  bracket  F,  the  whole  being  supported  by 
passing  through  tube  C°.  Spring  F^"^  being  attached  to 
stationary  tube  C°  by  means  of  bracket  C^  rod  F^  with 
bracket  F^  can  be  pressed  forward  until  pin  F^^  is  engaged 
by  notch  F^^. 

6.  By  loosening  set-screw  (7*  the  bracket  C  can  be  raised 
or  lowered  until  ball  D  with  its  supporting  stem  D^  is  in 
exact  alignment  with  the  center  of  the  cornea  of  the  af- 
fected eye,  and  the  screw  is  then  tightened. 

7.  The  patient  is  instructed  to  close  his  eyes,  and  the 
entire  instrument  with  its  base  is  slid  forward  until  in- 
dicator-ball D  presses  into  the  eyelid  approximately  its 
thickness.  The  trigger  F^'^  is  then  depressed  to  disengage 
notch  F-^  from  pin  F'^^,  when  spring  F^*^  will  cause  the  rod 


282  U.  S.  ARMY  X-RAY  MANUAL 

F^  and  indicator-ball  D  and  cone  E  to  rebound  exactly 
ten  millimeters,  being  restricted  by  knob  F''  in  slot 
C^.  The  subject  and  localizer  are  now  in  correct  position 
for  making  the  two  necessary  exposures. 

First  Exposure. — Place  patient's  head,  affected  eye 
downward,  on  the  plate-holder  base,  with  inflated  cushion 
in  position,  as  shown  in  illustration,  being  careful  that  the 
inflated  cushion  does  not  extend  over  the  marked  lines  on 
the  cover — otherwise  it  will  cast  a  shadow  on  the  photo- 
graphic plate. 

If  the  subject  shows  a  tendency  to  move  about,  the  hori- 
zontal clamp,  as  shown  in  Fig.  133,  must  be  adjusted  to 
the  base  of  the  head  and  forehead,  otherwise  the  vertical 
clamp,  as  shown  in  illustrations  herewith,  will  be  suffi- 
cient. The  double  horizontal  clamp  can  be  adjusted  for 
either  eye  by  means  of  its  two  off-center  holes  and  clamp 
screws. 

Place  the  diaphragmed  tube  in  position  so  that  its  cen- 
tral rays  will  exactly  parallel  the  front  vertical  plane  of  the 
patient's  eye,  as  shown  in  Fig.  135. 

A  plate,  having  previously  been  placed  in  the  plate-hold- 
er, is  now  placed  in  the  tunnel  with  the  outer  flange  pro- 
truding, as  shown  in  illustration.  This  will  expose  one- 
half  of  the  plate  to  the  action  of  the  rays,  while  the  other 
half  will  be  protected  for  the  second  exposure. 

The  localizer  (Fig.  134)  is  now  placed  on  the  stand  in 
front  of  the  affected  eye;  its  trigger  is  "set"  as  already 
described  and,  after  the  indicator-ball  has  been  adjusted 
to  the  plane  of  the  cornea,  the  entire  instrument  is  pushed 
forward  on  its  base  until  the  ball  presses  into  the  patient's 
closed  eyelid  approximately  its  thickness ;  the  trigger  spring 
is  then  released  and  the  indicator-ball  and  cone  recede  ex- 
actly 10  millimeters,  thereby  permitting  the  patient  to  open 
his  eyes  and  wink  them  in  a  natural  manner.    By  referring 


LOCALIZATION 


283 


to  localizer  chart  you  will  observe  that  due  allowance 
of  10  millimeters  has  been  made  by  placin^^  the  indicator- 
ball  and  cone  just  that  far  from  the  front  plane  of  the 


Fig.  135.  Position  for  first  exposure  in  localization  of  projectiles 
in  the  eye.  Be  certain  that  the  tube  is  centered  accurately  over  the 
cone  so  that  both  ball  and  cone  will  be  superimposed. 

cornea.  It  should  also  be  borne  in  mind  that  the  front 
of  the  cornea  is  10  millimeters  in  front  of  the  shadow  of 
the  indicator-ball,  as  shown  in  your  negatives.     The  tube 


284: 


U.  S.  ARMY  X-RAY  MANUAL 


is  now  centered  over  the  localizing  ball  and  cone  so  that 
the  shadows  of  the  two  will  coincide  (Fig.  135). 

Some  object,  such  as  a  candle  or  a  piece  of  white  paper, 
that  can  readily  be  seen  by  the  patient,  should  be  placed  in 
alignment  with  the  sights  of  the  indicator,  but  several  feet 
removed  therefrom,  and  the  patient  should  be  instructed 


Fig.  136.  Specimen  plate  of  projectile  in  the  eye  illustrating  the 
method  of  measurement. 

to  look  constantly  at  this  object  while  the  two  exposures 
are  being  made. 

Second  Exposure. — The  first  exposure  having  been 
made  with  the  rays  perpendicular  to  the  plane  of  the  plate 
and  parallel  to  the  patient's  eye,  thereby  superimposing 
the  shadows  of  the  indicator-ball  and  cone  and  their  sup- 
porting stems,  as  shown  in  the  right-hand  half  of  illustra- 
tion (Fig.  136)  the  x-ray  tube  is  then  shifted  toward  the 
patient's  feet  four  or  five  inches  and  tilted  so  that  the 
indicator-rod  points  to  the  ball  of  the  localizer,  thereby 


LOCALIZATION 


285 


causing  the  central  rays  to  pass  obliquely  through  the  cen- 
ter of  the  cornea  of  the  patient's  affected  eye,  as  shown  in 


Fig.  137.  Second  exposure  for  localization  of  projectiles  in  the 
eye.  Notice  shift  of  tube  in  order  to  separate  the  shadows  of  ball 
and  cone.  Be  careful  not  to  produce  any  lateral  shift.  The  tips  of 
ball  and  cone  must  be  kept  in  alignment. 


Fig.  137.  The  photographic  plate  must  now  be  shifted  by 
pushing  the  plate-holder  inward,  by  its  handle,  as  far  as 
it  will  go,  thereby  protecting  that  portion  that  was  acted 


286 


U.  S.  ARMY  X-RAY  MANUAL 


LOCALIZATION 


287 


r:3 


05 

CO 


O 
S 


288  U.  S.  ARMY  X-RAY  MANUAL 

upon  by  the  rays  in  the  first  exposure  and  bringing  its  un- 
exposed half  in  proper  position  to  receive  the  rays  from 
the  second  exposure.  In  this  position  the  second  exposure 
is  made  with  the  rays  falling  obliquely  upon  the  indicators, 
thereby  separating  their  shadows,  as  shown  in  left  half  of 
illustration. 

It  should  be  remembered  that  it  is  not  essential  that 
the  exposures  be  made  with  the  tube  at  any  specific  dis- 
tance from  the  plate,  or  even  that  it  be  the  same  distance 
for  the  two  exposures.  Neither  is  it  important  that  the 
tube  be  shifted  an  exact  or  known  distance  for  the  second 
exposure,  as  by  the  use  of  the  charts  and  Dr.  Sweet's 
method  the  course  of  the  ray  is  automatically  established. 
This  is  shown  by  the  line  A-D  through  P^  and  P^  of  out- 
line drawing,  Fig.  138. 

Charting  the  Plates. — In  charting  the  plates  the  follow- 
ing method  is  pursued:  Upon  the  negative  (right-hand  half 
of  the  illustration)  which  represents  the  first  exposure,  a 
line  is  drawn  through  the  horizontal  axis  of  the  indicator- 
ball  and  cone  which  are  here  superimposed,  thereby  pro- 
jecting their  supporting  stems  and  establishing  the  visual 
axis  of  the  eye.     Fig.  136. 

A  second  line  is  drawn  at  right  angles  to  the  first 
through  the  center  of  the  foreign  body's  shadow. 

With  a  small  pair  of  dividers  step  the  distance  from 
the  edge  of  the  indicator-ball  to  the  intersection  of  the 
horizontal  and  vertical  lines  that  you  have  just  drawn. 
Then  step  this  distance  off  on  the  diagram  chart,  making 
a  dot  with  a  pen,  or  a  very  sharp,  hard  pencil,  to  repre- 
sent the  exact  distance  (distance  R,  Fig.  138). 

On  the  vertical  line  that  has  been  drawn  through  the 
shadow  of  the  foreign  body  (right-hand  half  of  Fig.  136) 
measure  the  distance  of  the  foreign  body  above  or  below 


LOCALIZATION  289 

the  horizontal  line  and  indicate  the  same  on  the  chart 
above  or  below  the  axis,  distance  V  locating  dot  F^. 

Place  another  dot  on  the  same  horizontal  plane  and  draw 
a  line  through  these  two  dots,  parallel  to  the  axis,  project- 
ing into  the  front  view  as  shown. 

Since  the  position  of  localizer-ball  B,  as  shown  on  the 
chart,  side  view,  is  the  same  as  when  the  first  plate  was 
made,  the  location  of  the  foreign  body  must  be  at  point  F^. 
We  have  yet  to  establish  its  location  to  the  nasal  or  tem- 
poral side. 

Project  a  line  vertically  through  point  F^  to  the  45 
degree  angle  (see  Fig.  139),  thence  horizontally  through 
the  horizontal  section. 

Upon  the  negative  (left-hand  of  illustration)  which 
represents  the  second  or  oblique  exposure,  a  line  is 
drawn  through  the  horizontal  axis  of  both  the  ball  and 
the  cone,  thereby  projecting  their  supporting  stems  and 
establishing  the  relation  of  their  horizontal  planes  to  that 
of  the  foreign  body. 

A  third  line  is  drawn  at  right  angles  to  the  first  two 
through  the  center  of  the  foreign  body  shadow. 

With  your  dividers  measure  the  distance  of  the  shadow 
of  the  foreign  body  above  or  below  the  horizontal  plane 
of  the  shadow  of  the  ball,  and  mark  the  same  by  a  dot  on 
the  front  view  of  the  chart  just  above  or  below  the  center 
B,  as  indicated  by  distance  X,  because  that  was  the  relative 
position  of  the  indicator  ball  when  it  cast  the  shadow. 
Measure  the  distance  of  the  shadow  of  the  foreign  body 
above  or  below  the  horizontal  plane  of  the  shadow  of  the 
cone,  and  mark  the  same  on  the  chart  at  the  point  above 
or  below  C  indicated  by  distance  Y  because  that  was  the 
relative  position  of  the  indicator  cone  when  it  cast  the 
shadow. 

A  line  drawn  through  dots  P^  and  P^  will  represent 


290  U.  S.  AR:\IY  X-RAY  MANUAL 

the  true  course  of  the  rays  in  the  second  exposure,  and 
its  intersection  with  the  projected  line  from  the  side  view 
through  the  point  F^  will  be  the  position  of  the  foreign 
body  when  viewed  from  the  front,  while  a  vertical  projec- 
tion through  the  horizontal  section  shows  the  position 
of  the  foreign  body  to  the  nasal  or  temporal  side  at 
point  F. 

In  these  eye  localizations  a  source  of  error  is  the  fact 
that  this  is  a  schematic  eye,  constructed  to  correspond  to 
the  average  eye  which  is  about  24  millimeters  in  diameter, 
but  this  may  vary  3  millimeters  from  the  average. 

Sometimes  the  variation  can  be  measured  with  an 
opthalmoscope  and  corrections  made,  but  ordinarily  the 
eye  is  so  injured  that  this  is  impossible,  and  we  must  assume 
that  the  eye  corresponds  to  the  schematic  eye.  This  error, 
of  course,  would  interfere  only  in  those  cases  where  the 
foreign  body  is  located  1  or  2  millimeters  inside  or  outside 
the  sclera.  In  that  event  one  would  not  be  certain  whether 
the  foreign  body  was  within  or  without  the  globe  of  the 
eye. 

This  point  may  often  be  determined  in  the  following 
manner:  Place  the  patient  on  his  side  with  the  afflicted 
side  next  to  the  plate  and  center  the  tube  over  the  eye. 
Fix  the  vision  of  the  good  eye  on  a  spot  in  a  plane  paral- 
lel to  the  plate,  so  placed  that  the  eye  is  rotated  toward 
the  top  of  the  head.  Make  an  exposure  of  1/2  the  correct 
amount,  then  shift  the  vision  to  a  point  well  toward  the 
feet,  still  keeping  the  head  fastened  securely  in  place,  and 
expose  for  the  remainder  of  the  necessary  time. 

If  there  are  two  images  of  the  foreign  body,  it  is  certain 
that  the  foreign  body  moved  with  the  eye  and  therefore 
must  be  in  the  globe. 

It  is  barely  possible  for  the  foreign  body  to  be  in  an 
ocular  muscle  and  move,  thereby  giving  two  images,  but 


NEAREST   POINT   METHOD   OF  LOCALIZATION. 

(Insert  in  Manual  at  Page  291) 

Owing  to  the  enormous  pressure  of  work  on  the  roent- 
genologist in  an  advance  hospital  during  periods  of  great 
activity  on  the  front,  it  is  necessary  to  utilize  the  simplest 
and  most  rapid  method  of  localization  that  is  consistent 
with  working  accuracy.  One  method,  not  described  in  the 
manual,  that  has  met  considerable  favor  in  rapid  approxi- 
mate determination  of  location  and  depth  is  the  so-called 
"nearest  point"  method. 

This  method  consists  in  palpating  under  fluoroscopic 
observation  the'soft  tissue  surrounding  the  projectile.  .The 
instrument  used  for  this  palpation  is  a  wooden  rod  about 
ten  inches  long  with  a  wood  screw  or  some  similar  piece 
of  metal  at  the  end.  Under  the  screen  the  wood  is  almost 
invisible  and  the  only  plain  shadow  is  that  cast  by  the 
metal.  By  the  movement  of  the  projectile  under  pressure 
on  the  tissue  surrounding  it  and  the  amount  of  pressure 
used,  the  operator  is  able  to  judge  with  fair  accuracy  as 
to  what  point  on  the  skin  is  nearest  the  projectile  and  the 
depth  from  that  point.  Obviously,  palpation  at  a  very  near 
point  will  ordinarily  cause  much  greater  movement  of  the 
projectile  than  will  palpation  at  a  more  remote  part  of 
the  skin  surface.  Likewise,  palpation  will  cause  greater 
displacement  in  the  very  soft  tissues  than  it  will  in  the 
more  firm. 

Skill  in  this  method  increases  with  continued  use,  and  a 
sense  of  pressure  is  developed  that  proves  a  valuable  aid 


to  speed  and  accuracy.  To  the  beginner  with  this  method 
it  is  recommended  that  he  coin])iiie  witli  palpation  the 
principle  of  Method  B  by  shifting  his  tube  and  observing 
relative  displacements  of  the  projectile  and  the  palpating 
stick. 

The  nearest  point  method  is  applicable  to  localization  of 
projectiles  in  the  soft  tissues  of  the  extremities,  the  axilla, 
scrotum,  and  buttocks,  but  not  to  the  more  vital  and  less 
palpable  regions  of  the  iiead,  thorax,  and  abdominal  cavi- 
ties. By  practice  one  becomes  accustomed  to  palpating  the 
soft  tissues  around  the  foreign  body  and  by  what  are 
termed  light  and  deep  palpation  to  determine  the  depth 
of  the  projectile  from  the  nearest  point  on  the  skin  surface. 
Even  if  the  foreign  body  cannot  be  displaced  by  pressure 
with  the  palpating  stick  this  information  is  often  of  great 
value,  showing  that  the  projectile  must  be  in  a  joint, 
against  the  bone,  or  embedded  in  deep  tissue. 

This  method  is,  in  brief,  adapted  to  localization  in  the 
extremities  and  soft  parts  of  the  body,  under  advance 
hospital  conditions  where  rapid  examination  of  the  patients 
is  a  matter  of  prime  importance. 


LOCALIZATION  291 

its  position  near  the  exterior  and  anterior  portion  of  the 
globe  would  help  differentiate  this. 

In  an  acute  ease  where  a  localizing  apparatus  is  not 
available,  this  method  may  be  all  that  is  necessary. 


BONES  AND   JOINTS 

Fractures. — A  fracture  may  be  defined  as  a  break  in  the 
texture  of  a  bone  or,  more  briefly,  as  a  solution  of  con- 
tinuity. 

The  study  of  fractures  with  the  aid  of  the  x-ray  en- 
ables us  to  decide :  first,  whether  a  fracture  is  present 
or  absent;  second,  the  number  and  relation  of  the  broken 
fragments,  so  that  the  best  mechanical  measures  can 
be  selected  for  replacement.  After  a  retentive  dressing 
has  been  applied,  it  is  easy  to  study  the  results  of  treat- 
ment without  waiting  for  the  test  of  healing  and  restora- 
tion of  function. 

From  a  radiographic  standpoint  fractures  may  be  clas- 
sified into :  first,  simple  fractures,  where  the  bone  is  broken 
in  two  pieces;  second,  comminuted  fractures,  where  the 
bone  is  broken  into  many  pieces.  Simple  fractures  may 
be  further  classified  according  to  the  direction  of  the  frac- 
ture line :  first,  where  the  line  of  cleavage  is  transverse ; 
second,  oblique;  third,  longitudinal;  fourth,  combinations 
of  the  preceding  varieties.  Naturally  the  comminuted 
fracture  is  more  common  in  military  service  than  in  civil 
life.  In  military  service  there  is  to  be  seen  frequently 
the  effect  of  high-speed  bullets  upon  bones.  The  difference 
between  high-speed  projectiles  and  small  projectiles  of  low 
velocity  is  quite  striking.  In  the  former  the  results  simu- 
late an  explosive  action  evidenced  in  the  marked  com- 
minution and  shattering  of  the  osseous  tissue.  Small  lead 
bullets,  as  a  .22,  usually  cause  only  slight  injury  to  bones, 

292 


BONES  AND  JOINTS  293 

and  very  often  the  effect  of  the  contact  is  seen  rather  in 
the  deforming  of  the  bullet  than  in  the  shattering  of  the 
bone. 

Fractures  may  be  studied  by  the  x-ray  either  by  the 
fluoroscopic  method  or  by  the  plate  method.  Each  has  its 
advantages  and  disadvantages. 

Fluoroscopic  Method. — The  advantages  of  the  fluoro- 
scopic method  are,  primarily,  its  convenience  and  quick- 
ness of  execution,  without  the  delay  of  waiting  for  the 
development  of  plates.  It  allows  of  a  rapid  survey  of 
the  entire  body.  It  is  cheap  as  compared  with  the  cost 
of  a  number  of  plates.  Its  principal  disadvantage  lies  in 
the  fact  that  it  does  not  always  show  clearly  the  texture 
of  bones,  so  that  fractures  of  slight  displacement  are  not 
readily  shown.  This  is  especially  true  in  fleshy  individuals 
and  in  parts  of  the  body  where  the  bones  are  enveloped  in 
a  good  deal  of  soft  tissue.  Fractures  of  small  bones,  as 
transverse  fractures  of  the  scaphoid  or  longitudinal  frac- 
tures of  the  head  of  the  radius,  may  easily  escape  notice. 
Impacted  fractures  also  of  the  lower  end  of  the  radius 
and  of  the  surgical  neck  of  the  humerus  may  be  seen  so 
indistinctly  on  the  screen  that  there  may  occur  a  reason- 
able doubt  as  to  their  presence. 

Plate  Method. — The  chief  advantage  of  the  plate 
method  is  that  it  affords  an  exact  study  of  the  cancellous 
tissue  of  the  bones.  It  also  gives  a  permanent  record  of 
the  case,  so  that  the  condition  may  be  observed  by  others. 
As  in  the  examination  of  the  gastro-intestinal  tract,  the 
greatest  amount  of  information  is  often  best  obtained  by 
a  combination  of  the  two  methods. 

The  determination  of  the  part  of.  the  body  to  be  radio- 
graphed will  naturally  depend,  first,  upon  the  clinical 
history,  if  one  can  be  obtained,  and  second,  upon  the  usual 
signs  of  fracture  on  physical  examination.     If  a  patient 


294  U.  S.  AR]\rY  X-RAY  IMANUAL 

can  be  examined  on  the  fluoroscopic  table,  the  fluoroscope 
will  assist  in  deciding  on  the  area  to  be  radiographed.  It 
is  evident,  however,  that  some  types  of  subperiosteal  frac- 
ture, for  example,  fractures  of  the  lower  end  of  the  fibula, 
may  be  present  without  screen  evidence. 

In  radiographic  examination  of  fractures,  the  adherence 
to  a  routine  and  established  type  of  technique  is  of  con- 
siderable advantage.  One  of  the  most  essential  points  in 
this  technique  is  the  choice  of  a  suitable  ray;  by  this  is 
meant  a  ray  of  penetration  sufficient  to  properly  display 
the  internal  structure  of  the  bone.  Such  a  ray  will  be 
given  off  by  a  tube  having  an  equivalent  spark  gap  of  four 
to  five  inches.  Next  to  the  choice  of  the  proper  penetra- 
tion will  be  the  estimation  of  the  correct  time  of  exposure. 
The  next  factor  in  the  production  of  suitable  plates  is 
immobilization.  If  attention  is  not  paid  to  this,  the  twitch- 
ing of  the  wounded  muscles  and  the  voluntary  attempt  on 
the  part  of  the  patient  to  keep  the  part  quiet  will  result 
in  muscular  tremor  which  will  blur  the  bone  detail.  The 
immobilization  can  be  obtained  most  easily  by  weighting 
the  parts  above  and  below  the  area  to  be  examined  by  suit- 
able sand-bags.  These  sand-bags  should  not  be  completely 
filled.  They  can  then  be  packed  around  the  limb  in  order  to 
secure  the  greatest  quiet.  If  sand-bags  are  not  obtainable, 
the  use  of  strips  of  adhesive  plaster  above  and  below  the 
examined  area  will  be  found  useful.  AVide  bandages  passed 
around  the  part  and  then  tied  on  the  under  surface  of  the 
table  may  also  be  used.  If  one  is  working  with  the  tube 
above  the  table,  cotton  pads  or  an  inflated  rubber  bag  may 
be  placed  between  the  cone  of  the  tube-holder  and  the  af- 
fected part  for  compression. 

It  is  very  important  that  plates  should  be  labeled  at  the 
time  of  examination.  In  the  hurry  of  darkroom  technique 
plates  are  sometimes  reversed,  so  that  it  is  not  always  pos- 


BONES  AND  JOINTS  295 

sible  to  tell  at  a  glance  whether  the  plate  is  of  the  right 
or  left  leg.  Accordingly,  with  each  exposure  a  lead  letter 
1\  or  a  lead  letter  L  should  be  placed  upon  the  plate  to 
designate  which  limb  is  being  radiographed.  It  is  of  further 
advantage  in  lateral  plates,  especially  of  the  femur,  to  mark 
the  anterior  border  with  suitable  lead  letters,  so  that  the 
relative  position  of  the  fragments  can  be  told  at  a  glance. 
The  necessity  of  doing  this  arises  from  the  fact  that  often- 
times plates  are  examined  when  the  radiographer  is  ab- 
sent, and  those  observing  the  plates  may  not  be  skilled  in 
their  interpretation.  AYith  the  careful  labeling  of  plates 
serious  mistakes  may  often  be  avoided. 

In  examining  fractures  which  w^e  have  reason  to  sus- 
pect are  comminuted,  or  which  may  be  complicated  with 
the  presence  of  a  foreign  body,  the  value  of  stereoscopic 
plates  cannot  be  overestimated.  These  give  a  good  idea  of 
the  true  relation  of  the  fragments,  and  if  the  foreign  body 
is  present,  show  its  position  in  three  planes. 

Location  of  Tube. — In  considering  the  examination  of 
special  parts  of  the  body,  we  must  consider  the  technique 
from  two  separate  standpoints.  First,  the  examination  may 
be  conducted  with  the  patient  lying  upon  a  table,  the  tube 
being  placed  above  the  part  to  be  x-rayed  and  the  plate 
underneath.  Second,  if  the  examiner  is  provided  with  an 
apparatus  by  which  the  tube  is  contained  in  a  tube  box 
underneath  the  table,  the  rays  are  then  directed  from  be- 
low upward.  Each  method  has  certain  advantages  and  dis- 
advantages. The  advantage  of  the  first  position  is  that 
one  can  see  at  a  glance  the  relation  of  the  tube  to  the  part 
to  be  radiographed,  and  he  is  able  to  make  use  of  the 
central  rays.  The  advantage  of  using  the  central  rays  is 
to  minimize  distortion.  AYhile  this  distortion  may  have 
only  a  comparatively  slight  importance  in  plates  made 
of  simple  fractures,  yet  in  plates   of  comminuted   frac- 


296  U.  S.  ARMY  X-RAY  MANUAL 

tures,  especially  those  complicated  with  foreign  bodies, 
the  question  of  distortion  assumes  considerable  importance. 
A  further  advantage  of  using  the  tube  stand  is  that  in 
certain  parts  of  the  body  it  is  advantageous  to  employ 
oblique  rays.  For  example,  in  radiographing  the  foot,  it 
is  often  necessary  to  employ  oblique  radiation  in  order  to 
properly  separate  the  shadows  of  the  metatarsal  bones.  The 
degree  of  obliquity  and  the  angle  at  which  the  rays  will 
strike  the  part  examined  can  be  much  more  easily  told 
by  the  use  of  a  tube  stand  than  by  the  use  of  a  box  under- 
neath the  table  containing  the  tube.  Another  great  ad- 
vantage of  the  ordinary  tube  stand  is  that  the  tube  can 
be  shifted  so  that  the  rays  pass  laterally,  permitting  of 
lateral  exposures  of  the  ankle,  knee,  femur,  and  arm  with- 
out disturbance  of  the  patient.  In  fractures  of  the  femur 
and  knee  with  plates  made  at  the  bedside  of  the  patient, 
this  will  oftentimes  be  a  point  of  great  advantage.  The 
disadvantages  of  this  method  are,  first,  the  necessity  of 
raising  the  limb  to  insert  the  plate  underneath,  and,  sec- 
ond, the  necessity  of  protecting  the  plate  from  moist  dress- 
ings. This  objection  can  be  easily  overcome  by  placing  the 
plate  in  an  aluminum  plate-holder. 

The  advantages  of  working  with  the  tube  beneath  the 
table  are  the  fact  that  the  plate  can  be  supported  imme- 
diately above  the  injured  member  and  that  no  lifting  of 
the  limb  while  the  patient  is  on  the  table  is  necessary.  If 
the  tube  box  below  the  table  is  used,  it  is  necessary  to  have 
some  mechanical  pointer  attached  to  the  box  so  that  one 
knows  the  axis  of  the  central  rays.  In  the  making  of 
stereoscopic  radiograms  many  operators  prefer  the  tube 
above  the  patient.  Most  of  the  types  of  American  ap- 
paratus are  made  for  radiographing  the  patient  from  above 
downward,  while  many  of  the  types  of  the  Continental 
and  the  English,  have  the  tube  below  the  table. 


BONES  AND  JOINTS  297 

Position  for  Exposure. — The  illustrations  show  briefly 
the  positions  in  which  the  different  parts  should  be  radio- 
graphed. These  positions  may  be  adopted  as  a  routine  in 
the  majority  of  cases,  and  there  is  an  advantage  in  follow- 
ing a  routine  plan.  The  individual  case  may,  however, 
demand  a  departure,  in  which  case,  a  safe  rule  to  follow 
is  that  the  injured  part  should  be  as  close  to  the  plate 
as  possible  and  the  vertical  ray  should  enter  immediately 
over  the  center  of  this  area. 

The  comfort  of  the  patient  must  be  kept  constantly  in 
mind,  and  if  an  arm  cannot  be  completely  extended,  it  is 
possible  to  demonstrate  lateral  displacement  of  fragments 
by  the  anteroposterior  exposure  even  if  the  elbow  is  flexed 
at  a  right  angle.  The  point  to  remember  is,  that  it  is  im- 
possible even  with  stereoscopic  plates  to  tell  accurately  the 
amount  of  displacement  that  may  be  present  in  the  region 
of  a  joint,  such  as  an  elbow  or  knee,  if  the  plates  have 
been  made  in  one  direction  only. 

In  the  case  of  the  spine  the  best  results  are  obtained 
by  raying  a  comparatively  small  area  at  a  time  with  a 
medium  sized  cone.  For  the  lateral  view  it  is  almost  es- 
sential that  one  should  use  an  intensifying  screen  and 
remove  the  tube  to  a  considerable  distance  from  the  plate, 
at  least  thirty  inches. 

Radiographs  Made  Through  Splints  or  Casts. — In  radio- 
graphing parts  of  the  body  enveloped  in  splints  or  casts, 
there  is  presented,  oftentimes,  a  difficult  problem.  For 
purposes  of  exact  diagnosis  it  is  always  best,  w^hen  possible, 
to  remove  any  splints  or  casts.  If  the  examination  is  made 
for  determining  the  position  after  reduction,  the  dressing 
should  be  left  on.  The  length  of  exposure  is  to  be  in- 
creased so  as  to  compensate  for  the  extra  amount  of  mate- 
rial which  has  to  be  penetrated.  Some  splint  materials, 
for  example,  yucca  board,  contain  particles  of  extra  den- 


298  U.  S.  ARMY  X-RAY  MANUAL 

sity  which,  when  superimposed  on  the  shadows  of  the  bone, 
render  the  detection  of  subperiosteal  fractures  difficult. 
It  often  occurs  that  the  radiographer  has  to  decide  whether 
callus  is  present  or  absent  in  a  limb  enveloped  in  a  plaster 
splint.  It  can  be  stated  tliat  this  is  oftentimes  impossible 
to  be  decided,  as  the  varying  densities  of  the  folds  of 
plaster  induce  shadows  which  may  simulate  the  appear- 
ance of  callus.  Sometimes  when  a  limb  has  a  splint  on 
one  side  only,  the  rays  can  be  directed  so  that  the  shadow 
of  the  bone  can  be  wholly  or  partly  isolated  from  the 
shadow  of  the  splint.  In  elbows  confined  with  a  right- 
angle  metallic  splint,  the  metal  may  cast  a  shadow  over 
the  part  especially  interesting,  and  here  in  the  interest  of 
exact  diagnosis  it  is  best  to  secure  permission  to  remove 
the  splint.  Dry  plaster  is  more  easily  penetrated  by  the 
ray  than  moist  plaster,  so  that  it  is  always  best  to  x-ray 
a  limb  in  a  plaster  cast  after  the  cast  has  become  thor- 
oughly dry.  The  position  of  the  fragments  of  long  bones 
of  course  can  be  accurately  told  even  when  enveloped  in  a 
wet  plaster  cast,  but  it  is  not  to  be  expected  that  fine 
detail  and  the  presence  or  absence  of  callus  can  be  made 
out  without  the  removal  of  the  cast.  Where  the  examina- 
tion has  to  be  made  in  only  one  direction  the  plates  should 
be  stereoscopic. 

Splints,  casts,  dressings,  'bandages,  etc.,  should  never  he 
disturbed  by  the  roentgenologist.  If  they  have  to  be  re- 
moved, this  should  be  done  by,  or  under  the  direction  of, 
the  surgeon. 

The  Appearance  of  Callus. — Changes  in  the  periosteal 
surface  appear  very  early  after  injury,  sometimes  being 
seen  after  a  period  of  four  or  five  days.  These  periosteal 
changes  vary  in  proportion  to  the  amount  of  displacement. 
If  a  fracture  is  of  the  subperiosteal  type,  or  if  the  frag- 
ments have   been   accurately   coapted,   periosteal   changes 


BONES  AND  JOINTS  299 

will  be  small,  and  not  extend  far  from  the  seat  of  frac- 
tnre.  If  the  fracture  is  transverse,  with  over-riding,  or 
if  it  is  comminuted  with  displacement,  we  may  find  perios- 
teal changes  extending  a  number  of  inches  away  from  the 
seat  of  injury.  We  often  find,  especially  in  the  lower  leg, 
difficulty  in  telling  whether  there  has  been  enough  repair 
to  allow  the  patient  to  walk  upon  the  leg.'  Careful  inspec- 
tion of  the  plate  may  show  nothing  but  the  position  of  the 
fragments,  without  any  periosteal  change.  In  these  cases, 
it  is  difficult  to  tell  from  the  radiogram  alone  whether  union 
has  taken  place. 

Reports. — In  waiting  reports  of  x-ray  plates  for  frac- 
tures, it  is  essential  to  describe  first  the  area  shown  by  the 
plate  with  the  anatomic  parts  of  the  bone  examined; 
second,  to  give  a  description  of  the  traumatic  pathology 
shown;  third,  a  statement  as  to  the  condition  of  the  bone, 
or  bones,  and  of  the  soft  parts  outside  of  the  area  described 
in  the  second  heading.  In  the  report  the  manner  in  which 
the  plate  is  made  should  be  described  so  that  this  can  be 
taken  account  of  in  considering  the  interpretation.  For 
example,  if  a  lateral  plate  is  made,  this  fact  should  be  men- 
tioned at  the  beginning  of  the  description.  A  description 
of  the  traumatic  pathology  should  embrace,  first  of  all,  the 
part  of  the  bone  involved;  second,  the  type  of  fracture, 
whether  transverse,  oblique  or  longitudinal ;  third,  whether 
comminution  is  present  and  the  number  and  size  of  the 
fragments.  In  all  cases  the  relative  position  of  the  frag- 
ments should  be  described.  If  the  fracture  is  complicated 
by  the  presence  of  a  foreign  body,  this  should  be  stated, 
with  the  size,  shape  and  position,  and  its  relative  position 
to  the  bone  fragments. 

Particular  attention  should  'be  paid  to  the  question  as  to 
jivhether  the  fracture  line  involves  joint  surfaces.    Prog- 


300  U.  S.  ARMY  X-RAY  MANUAL 

nosis  and  treatment  are  materially  affected  in  this  type 
of  injury. 

If  it  is  doubtful  after  an  examination  of  all  the  plates 
whether  a  fracture  is  present  or  absent,  this  doubt  should 
be  plainly  stated  and  the  reasons  for  it  given.  If  the  un- 
certainty is  based  on  lack  of  penetration  or  blurring  due 
to  movement,  a  second  exposure  should  be  made.  If  splints 
v^ere  present  at  the  time  of  examination,  their  appearance 
should  be  described  and  special  note  made  as  to  whether 
the  shadow  of  the  splint  complicates  the  interpretation. 

Negcative  Reports. — If  the  examination  does  not  reveal 
the  ordinary  x-ray  evidences  of  fracture,  this  should  be 
stated  with  a  definite  description  of  the  area  shown  by  the 
plate.  For  example,  a  negative  report  stating  that  there 
is  present  no  fracture  of  the  tibia  or  fibula  should  not  be 
made  unless  the  plate  shows  the  entire  length  of  the  tibia 
and  fibula.  If  the  limb  is  rayed  in  only  one  direction, 
note  should  be  made  of  this  and  the  conclusion  should  be 
stated  that  no  disturbance  of  the  outline  of  the  bone  is 
shown  in  this  one  view. 

X-Ray  Osteology. — To  become  proficient  in  the  inter- 
pretation of  plates,  constant  use  should  be  made  of  the 
drawings  and  descriptions  in  standard  anatomies,  supple- 
mented, if  possible,  by  recourse  to  the  study  of  the  skeleton. 

Epiphyses. — While  in  military  radiography  the  question 
of  the  appearance  of  the  bones  during  their  development 
will  not  often  be  raised,  yet  it  is  best  to  remember  that 
during  the  growing  period,  when  the  bones  are  in  forma- 
tion, their  appearance  may  be  different  from  the  fully 
formed  adult  type.  The  different  standard  anatomies  give 
tables  under  which  are  described  the  development  of  the 
bones  and  the  age  at  which  the  epiphyseal  lines  become 
ossified.  In  the  young  adult  the  appearance  of  the  crest 
of  the  ilium  should  be  borne  in  mind,  as  ossification  here 


BONES  AND  JOINTS  301 

takes  place  at  the  age  of  eighteen  to  twenty.  In  cases  of 
doubt  as  to  whether  the  epiphyseal  line  is  to  be  differen- 
tiated from  a  fracture  line,  a  plate  made  of  the  uninjured 
limb  for  purposes  of  comparison  is  of  the  utmost  impor- 
tance. 

Plate  Defects. — The  interpreter  of  x-ray  plates  should 
be  constantly  on  his  guard  against  confusing  plate  defects 
with  fracture  lines.  While  it  is  unusual  for  such  con- 
fusion to  arise,  still,  scratches  upon  the  plates  have  been 
mistaken  for  solutions  of  continuity;  artefacts  due  to  air 
bubbles  have  been  confused  with  foreign  bodies. 

Conclusions  to  Be  Drawn  from  Plates  Influencing  Meth- 
ods of  Re-position. — It  can  be  said  that  some  clinicians  do 
not  derive  from  the  study  of  the  plates  all  the  information 
which  the  plates  afford.  Here  the  conference  between 
the  experienced  roentgenologist  and  the  clinician  is  of  the 
greatest  benefit  to  the  patient.  A  careful  study  of  the  plate, 
with  a  full  understar  ^  Ing  of  the  problems  of  re-position, 
will  oftentimes  obviate  the  question  of  operative  interfer- 
ence. 

Setting  of  Fractures  under  the  Fluoroscope. — In  the 
reduction  of  fractures  the  aid  of  the  fluoroscope  during 
manipulation  may  be  of  value.  Important  precautions  are, 
however,  to  be  observed  in  this  procedure.  If  the  patient 
is  under  ether  anesthesia,  precautions  should  be  taken 
against  the  ignition  of  the  ether  vapor  by  electric  sparks 
from  the  high  tension  current.  The  danger  of  this  is  in 
direct  proportion  to  the  lack  of  ventilation  in  the  operating 
room.  If  the  high  tension  wires  are  covered  with  thick 
insulating  material  and  loose  connections  are  avoided  so 
that  there  is  no  tendency  for  sparks  to  occur,  the  danger 
is  minimized. 

The  operator  and  his  assistant  should  be  protected  as 
completely  as   possible   against   radiation.     This  may  be 


302  U.  S.  ARMY  X-RAY  IMANUAL 

done  by  the  use  of  x-ray  proof  gloves,  x-ray  proof  aprons, 
suitable  lead  glass  over  the  fluoroscopic  screen,  and  the 
use  of  as  small  a  cone  of  x-ray  light  as  will  enable  the 
ends  of  the  bones  to  be  properly  seen.  While  this  method 
is  of  great  value  when  properly  done,  yet  one  should  be 
slow  about  drawing  inferences  as  to  correct  position  from 
fluoroscopic  examination  in  a  single  direction. 

Radiographs  with  Patient  in  Bed. — It  often  occurs  that 
in  patients  whose  general  condition  does  not  warrant  their 
removal  to  the  radiographic  table,  the  x-ray  examination 
should  preferably  be  made  with  the  patient  in  his  bed.  It 
also  happens  that  after  a  reduction  has  been  made  and 
extension  has  been  present  for  a  number  of  hours,  it  is 
highly  desirable  to  find  out  if  the  fragments  are  in  posi- 
tion. If  the  patient  is  moved  to  the  x-ray  room  and  the 
extension  discontinued,  it  is  obvious  that  the  plates  ob- 
tained may  not  represent  the  true  condition  of  the  frag- 
ments as  afforded  by  the  treatment  in  the  patient's  bed. 
The  standard  army  bedside  unit  was  designed  especially 
to  take  care  of  this  class  of  work  without  disturbing  the 
patient  more  than  is  absolutely  necessary.  It  is,  of  course, 
not  always  possible  to  make  the  examination  fluoroscopic- 
ally  at  the  bedside  owing  to  the  presence  of  the  bed,  which 
is  likely  to  contain  metal.  In  msmy  cases,  however,  a  lateral 
view  may  be  secured  fluoroscopically,  and  radiographic 
work  can  be  done  from  above  downward  or  laterally  with- 
out difficulty.  It  should  be  observed  that  the  limitations 
formerly  present  on  portable  apparatus  such  that  heads, 
hips,  etc.,  could  not  be  successfully  radiographed  do  not 
apply  to  this  unit.  By  using  the  proper  exposure,  either 
with  or  without  intensifjdng  screens,  radiographs  of  all 
parts  of  the  body  may  be  successfuly  made,  provided  the 
part  can  be  immobilized.  It  will  be  found  that  with  good 
intensifvino^  screens  and   double-coated  films  the  time  of 


BONES  AND  JOINTS  303 

exposure  will  differ  but  little  from  that  used  with  the  large 
machines  without  screens. 

Dislocations. — Examinations  of  the  body  for  the  deter- 
mination as  to  whether  a  dislocation  is  present  or  absent 
involve  the  same  general  applications  of  radiography  as 
in  the  determination  of  the  presence  of  fractures.  The 
same  principles  of  suitable  penetration  of  the  rays,  im- 
mobilization as  completely  as  possible  of  the  part  under 
examination,  the  employment  of  the  stereoscopic  method, 
and  care  in  the  interpretation  of  the  plates  obtained  possess 
equal  importance.  In  the  detection  of  dislocations,  the 
fluoroscopic  method  is  of  value  in  dislocations  of  the  larger 
joints,  as  the  shoulder,  the  elbow,  knee  and  ankle.  Dis- 
locations of  the  carpal  bones  and  the  metatarsal  bones  are 
not  usually  seen  easily  with  the  fluoroscope.  The  advan- 
tage of  the  fluoroscopic  method  in  examination  of  the  large 
joints,  for  example,  the  shoulder,  lies  in  the  fact  that  the 
position  of  the  tube  is  easily  shifted  so  that  the  rays  will 
strike  the  joint  at  different  angles.  An  observation  of 
the  shoulder  joint  from  one  angle  may  produce  a  dis- 
tortion which  may  be  deceiving.  In  general,  it  may  be 
said  that  the  central  rays  should  go  through  the  joint 
surface  under  examination,  and  that  they  should  strike 
the  plate  at  a  perpendicular.  Oblique  radiation,  when 
used,  should  have  its  results  interpreted  very  carefully. 

Reduction  of  Dislocations  with  Fluoroscopic  Aid. — Re- 
duction of  dislocations  under  fluoroscopic  guidance  is  es- 
pecially advantageous;  the  operator  can  see  constantly 
the  relation  of  the  two  articulating  surfaces  and  better 
plan  his  attempts  at  reduction.  It  is  obvious  that  the 
same  precautions  should  be  observed  as  in  manipulation 
of  fractures  under  the  fluoroscope.  In  all  dislocations  of 
large  joints  it  is  best  to  have  stereoscopic  plates  of  the 
joint,  not  only  to  determine  the  relative  positions  of  the 


30i  U.  S.  ARMY  X-RAY  MANUAL 

articular  surfaces  but  also  to  determine  their  inte^ity. 
Sprain  fractures  are  a  frequent  complication  of  disloca- 
tions, and,  if  they  can  be  detected,  this  knowledge  assists 
materially  in  making  the  prognosis. 

Fluoroscopy  vs.  Radiography. — In  fractures  and  dislo- 
cations radiography  is  the  method  of  choice,  since  it  reveals 
detail  impossible  to  obtain  on  the  screen  and  forms  a  per- 
manent record.  The  chief  value  of  the  fluoroscopic  method, 
which  can  demonstrate  only  gross  lesions,  lies  in  its  sim- 
plicity, speed,  and  comparative  inexpensiveness.  It  is  of 
value  in  positive  diagnosis  but  is  absolutely  of  no  value 
when  the  findings  are  negative. 

Fracture  of  the  Skull. — The  shape  of  the  skull  and  its 
elasticity,  the  close  fitting  covering  of  skin,  muscle,  fascia 
and  periosteum  on  the  outside,  and  the  pressure  of  the 
intracranial  contents  and  the  dura  on  the  inside,  tend  to 
immediately  replace  and  maintain  fractures  in  position. 
For  this  reason,  we  find  fractures  indicating  only  slight 
bony  injury,  the  grave  lesion  being  to  the  blood  vessels, 
intracranial  nerves,  dura  and  brain  substance  and  the 
secondary  conditions  arising  therefrom;  the  presence  or 
absence  of  fracture,  in  such,  cases,  fades  into  insignificance 
except  as  a  clue  to  the  site  of  the  injury  and  a  guide  for 
surgical  procedure. 

Varying  from  this  class,  we  have  the  other  extreme ; 
namely,  those  having  an  extensive  bony  lesion,  as  in  de- 
pressed or  perforating  fractures,  with  or  without  injury 
to  the  underlying  structures.  In  such  cases,  the  location 
and  character  of  the  fracture  must  be  considered.  Here 
the  force  is  consumed  in  breaking  bone  at  the  point  of 
contact,  the  effect  being  dependent  upon  the  amount  of 
force,  the  point  of  injury  and  the  character  of  the  body 
producing  the  fracture. 

Between  the  two  definite  forms  above  mentioned,  there 


BONES  AND  JOINTS  305 

is  much  variance  in  the  importance  of  the  bony  injury. 

Fractures  of  the  skull  may  be  divided  into  those  of  the 
vault  and  those  involving  the  base.  In  over  fifty  per  cent 
of  the  cases  examined  radiogTaphically  there  is  found  a 
combination  of  both.  Fracture  of  the  vault  may  be  due 
to  direct  or  indirect  violence  or  it  may  be  an  extension  from 
the  base.  There  have  been  various  theories  advanced  re- 
lating to  these  fractures,  such  as,  Aran's  theory  of  irradia- 
tion, the  bursting  theory,  fractures  by  contrecoup  and  the 
Rawling  theory  of  direct  violence.  It  would  seem  as  though 
each  applied,  as  a  causative  factor,  to  certain  classes  of 
fracture  of  the  skull.  Experience  shows  that  cases  which 
are  able  to  reach  the  roentgenologist  present  a  fairly  con- 
stant effect  of  clirect  violence,  the  point  of  impact  receiv- 
ing the  maximum  amount  of  bony  injury ;  from  this  point, 
we  have  radiating  fracture  lines  which  seek  the  weaker 
parts  of  the  skull  in  the  immediate  neighborhood. 

The  common  fractures  of  the  skull  are  described  as : 
fissured,  comminuted,  diastasis  of  the  sutures,  depressed  and 
perforated.  The  frequency  with  which  these  fractures  are 
mistaken  for  various  other  conditions,  especially  in  cases 
of  coma,  calls  for  a  method  which  will  make  a  rapid  and 
positive  diagnosis.  On  account  of  the  many  difficulties 
which  are  encountered  in  the  correct  diagnosis  of  head 
lesions  the  routine  x-ray  examination  of  the  skull  is  of 
the  greatest  importance  in  all  head  injuries.  It  offers  an 
actual  visual  demonstration  of  the  presence  or  absence  of 
fracture,  its  location,  character  and  extent. 

Traumatic  skull  injuries  should  have  systematic  x-ray 
examination.  If  such  examinations  were  made  in  all  cases 
of  head  injuries,  statistics  would  show  a  much  greater 
percentage  of  fractures  than  at  present.  In  a  series  of 
300  cases  in  the  writer 's  experience,  twenty  per  cent  showed 
fracture. 


306  U.  S.  ARMY  X-RAY  MANUAL 

When  a  case  of  head  injury  is  referred  to  the  roent- 
genologist for  examination,  the  patient  is  often  in  an  irri- 
table, semiconscious  or  comatose  condition.  Extreme  pa- 
tience and  perseverance  are  required,  and  it  is  even  fre- 
quently necessary  to  administer  a  hypodermic  of  Ma- 
gendie's  solution.  It  must  be  borne  in  mind  that  the 
minimum  amount  of  distur'bance  and  movement  is  essential. 

In  skull  examinations,  the  patient's  head  must  be  abso- 
lutely fixed  and,  if  possible,  all  respiratory  movement  over- 
come. If  the  objective  symptoms,  such  as  bleeding  from 
the  ear,  nose  or  mouth,  laceration  of  the  scalp,  hematoma 
or  paralysis  be  present,  they  are  a  clue  to  the  possible  site 
of  the  fracture,  and  attention  is  naturally  directed  toward 
that  area ;  this  must  not  mislead  one,  however,  for  every 
examination  should  cover  the  frontal,  the  parietotemporal, 
the  occipital  and  basilar  regions. 

It  should  be  constantly  borne  in  mind  that  examination 
of  the  skull  requires  a  considerable  amount  of  radiation 
for  each  plate  taken.  On  this  account  it  is  absolutely  neces- 
sary to  use  at  least  one  millimeter  of  aluminum  as  a  filter 
and  to  keep  in  mind  the  cumulative  effect  of  the  exposures 
and  the  fact  that  the  areas  receiving  radiation  during  the 
different  examinations  overlap  to  some  extent. 

Where  the  required  current  of  40  ma.  at  a  5-inch  gap 
cannot  be  secured,  one  should  not  attempt  to  do  the  work 
at  a  lower  gap,  but  should  maintain  the  gap  at  the  ex- 
pense of  current.  Thus,  if  one  must  use  5  ma.  instead  of 
40,  still  at  a  5-inch  gap,  the  time  of  exposure  at  the  same 
distance  must  be  eight  times  as  long.  For  10  ma.  four 
times  as  long.  The  objectionable  feature  in  this  procedure 
is  the  increased  difficulty  of  immobilization  for  the  longer 
periods. 

Frontal  Region. — In  the  examination  of  the  frontal 
region,  we  should  endeavor  to  show  as  much  of  the  vertical 


BONES  AND  JOINTS 


307 


plate  of  the  frontal  bone  as  possible.  The  patient  is  placed 
on  the  table  fiat  on  the  abdomen  with  face  resting  on  the 
plate.  The  glabella  should  be  in  contact  with  the  plate. 
An  imaginary  line  running  through  the  glabella  and  sym- 
physis of  the  jaw  should  be  parallel  to  the  axis  of  the  plate. 
The  head  should  then  be  firmly  fixed  either  by  clamps  or 


Pig.  140.     Position  for  examination  of  frontal  region  of  skull. 


sand-bags,  care  being  taken  not  to  rotate  the  head  during 
this  immobilization.  The  tube  should  then  be  adjusted  so 
that  the  ray  through  the  center  of  the  diaphragm  passes 
through  the  center  of  the  glabella.  Target-plate  distance 
should  be  about  22  inches.     Fig.  1-iO. 

A  5-inch  spark-gap  is  used,  forty  to  forty-five  milli- 
amperes  and  an  exposure  of  about  six  to  eight  seconds.  In 
the  majority  of  cases  this  procedure  will  give  satisfactory 
plates  of  the  frontal  region. 


308 


U.  S.  ARMY  X-RAY  MANUAL 


If  circumstances  require  the  use  of  the  portable  table, 
the  fluoroscopic  screen  should  be  replaced  by  the  tube 
holder.  Should  it  be  necessary  to  use  the  portable  outfit 
with  a  5-inch  gap  and  ten  milliamperes,  the  exposure 
would  be  about  thirty  to  thirty-five  seconds.  The  bedside 
unit   being   limited   to    5-inch   spark-gap    and   five    milli- 


FiG.  141.     Position  for  examination  of  temporoparietal  region  of 
skull. 


amperes,  it  would  be  best  to  use  an  intensifying  screen  and 
a  properly  modified  exposure. 

Temporoparietal. — In  examining  the  temporoparietal 
region,  we  should  show  that  portion  of  the  skull  lying 
between  the  sagittal  suture  above,  the  coronal  suture  an- 
teriorly, the  lambdoid  suture  posteriorly  and  including  the 
entire  temporal  bone.  Both  sides  of  the  head  must  be  ex- 
amined. The  patient  lies  on  his  side  with  neck  slightly 
extended,  the  center  of  the  temporal  region  resting  upon 


BONES  AND  JOINTS 


309 


the  plate.  The  head  is  raised  or  lowered  until  a  line  ex- 
tending from  the  glabella  to  the  symphysis  of  the  lower 
jaw  is  parallel  with  the  plate.  The  tube  is  adjusted  over 
the  center  of  the  temporal  region,  perpendicular  to  the 
plate  at  a  distance  of  twentij-four  inches.  The  head  should 
be  securely  clamped  or  held  by  a  weighted  bandage.  Fig. 
141. 


Fig.  142.     Position  for  examination  of  posterior  (occipital)  region 
of  skull. 


The  same  electrical  conditions  govern  the  tube  as  when 
examining  the  frontal  region,  except  that  it  is  seldom  neces- 
sary to  make  the  exposure  longer  than  three  or  four  seconds. 

Posterior  Region. — When  examining  the  posterior  re- 
gion, we  must  bring  out  with  clear  detail  the  entire  occipi- 
tal bone,  with  the  lambdoid  sutures  like  an  inverted  V 
above,  the  mastoids  on  either  side  and  the  foramen  mag- 
num below.    The  patient  lies  on  his  back  on  the  top  of  the 


310  U.  S.  ARMY  X-RAY  MANUAL 

table  with  the  occiput  flat  down  on  the  plate,  the  center  of 
the  occipital  bone  being  placed  in  contact  with  the  plate. 
The  head  should  be  slightly  flexed  so  that  the  central  ray 
(tube  tilted  15°  toward  the  feet)  enters  the  forehead  just 
above  and  between  the  frontal  eminences.  If  a  cone  is 
used,  the  lower  border  of  the  cone  should  not  extend  be- 
low the  supraorbital  ridges.  The  head  is  clamped  or  held 
in  position  by  a  weighted  bandage.  Fig.  142.  An  expo- 
sure of  about  nine  seconds  is  made  with  a  tube  taking 
about  forty  milliamperes  and  with  a  gap  of  five  inches. 

Base  Region. — In  cases  of  suspected  fracture  of  the  base 
the  vertical  technique,  as  advocated  by  D.  R.  Bowen  for 
examination  of  the  sphenoidal  sinuses,  may  be  used  with 
slight  modification. 

To  carry  out  this  method  it  is  necessary  to  elevate  the 
shoulders  a  few  inches  so  that  extension  of  the  neck  is 
obtained.  The  head  should  be  so  placed  that  a  line  drawn 
from  the  glabella  to  the  external  auditory  meatus  is  parallel 
to  the  plate. 

The  tube  is  then  adjusted  so  that  the  central  ray  through 
a  two-inch  opening  in  a  lead  diaphragm  is  centered  midway 
between  the  midlarynx  and  the  symphysis  of  the  jaw. 
This  central  ray  will  be  in  a  plane  about  one  inch  in  front 
of  the  external  auditory  meatus.  The  target  should  be  at 
a  distance  of  about  twenty-two  inches  from  the  plate  or 
film.  The  patient's  head  must  be  securely  immobilized  and 
clamped  if  necessary.  Fig.  143.  With  the  tube  taking 
forty  milliamperes  at  a  5-inch  gap,  an  exposure  of  about 
ten  seconds  will  be  required. 

Having  obtained  satisfactory  plates,  it  is  necessary  to 
have  the  experience  and  anatomical  knowledge  to  make  the 
correct  interpretation.  In  reading  plates  of  the  base  of 
the  skull,  beginning  behind,  we  see  the  foramen  magnum 
and  within  it  the  odontoid  process  of  the  axis.     Just  for- 


BONES  AND  JOINTS 


311 


ward  of  this  opening,  on  either  side,  the  mastoids  are  dis- 
tinctly reproduced  with  the  associated  shadows  of  the 
petrous  portion  of  the  temporal  bone.  Anterior  to  this  is 
a  clear  view  of  the  middle  fossa.  If  the  chin  is  not  too 
extended,  the  anterior  fossa  can  be  seen  in  front  of  the 
overlying  shadow  of  the  lower  jaw.    Fractures  of  the  zygo- 


FiG.  143.     Position  for  examination  of  basilar  region  of  skuU. 


matic  arch,  with,  the  extent  of  displacement,  are  usually 
beautifully  shown  in  radiograms  of  the  base. 

In  the  interpretation  of  the  frontal,  lateral  and  occip- 
ital regions  one  must  note  the  suture  markings  and  the 
normal  radiating  lines  cast  by  the  grooves  on  the  inner 
table  of  the  skull,  which  accommodate  the  meningeal  ves- 
sels ;  these  grooves  spread  fan-shaped  from  an  anterior  point 
backward.    The  shadows  cast  by  the  diploic  spaces,  between 


312  U.  S.  ARMY  X-RAY  ^MANUAL 

the  inner  and  outer  tables  of  the  skull,  are  lines  extending 
vertically  upward  from  the  base,  interlacing  at  the  top 
and  terminating  as  a  rule  in  an  anterior  and  a  posterior 
lake.  They  are  directly  at  variance  with  the  shadows  rep- 
resenting the  meningeal  grooves. 

Fractures  usually  show  as  dark,  sharply  cut  lines  of 
varying  width,  depending  upon  the  extent  of  separation ; 
they  may  be  vertical,  horizontal  or  curved,  but  seldom 
directed  in  the  same  manner  as  the  blood  vessel  grooves. 

In  addition,  we  wish  to  especially  emphasize  the  value 
of  the  stereoscopic  examination  in  these  head  injuries.  It 
is  often  difficult  in  cases  of  slight  depression  for  the  sur- 
geon to  decide  whether  to  interfere  or  not.  The  presence 
or  absence  of  symptoms  of  intracranial  pressure  and  the 
actual  demonstration  of  the  condition  of  the  inner  table  of 
the  skull,  with  the  amount  of  depression,  if  any,  are  vital 
facts  which  should  be  considered  before  a  decision  is  made. 

Lateral  stereoscopic  plates  aid  in  tracing  the  fracture 
line  into  the  base  and  locating  the  termination.  In  the 
common  penetrating  fractures  of  the  vertical  plate  of  the 
frontal  bone  and  those  cases  of  linear  fracture  extending 
into  the  roof  of  the  orbit,  they  are  of  extreme  value,  as 
giving  the  most  accurate  estimate  of  the  seriousness  of 
the  bony  injury. 

Examination  of  Spine. — On  account  of  the  importance 
and  frequency  of  spinal  injuries,  some  special  instruction 
may  be  found  desirable.  The  roentgenologist  who  is  un- 
familiar with  the  indications  of  anatomy  as  shown  on  the 
x-ray  plate  with  reference  to  the  spine  would  do  well  to 
review  carefully  the  anatomy  and  study  with  considerable 
care  plates  made  of  normal  individuals  in  which  the  spine 
is  clearly  shown.  Attention  is  also  called  to  paragraph 
on  page  320  with  reference  to  certain  abnormalities  which 
are  of  frequent  occurrence. 


BONES  AND  JOINTS  313 

Generally  speaking,  fluoroscopic  examination  is  of  little 
value  in  examinations  of  the  spine  on  account  of  the  thick- 
ness of  tissue  and  the  necessarily  small  degree  of  contrast 
which  may  be  secured.  It  is  frequently,  however,  of  value 
to  use  a  small  screen  in  the  examination  of  the  cervical 
region. 

On  account  of  the  considerable  number  of  bony  projec- 
tions and  spinous  processes  and  the  peculiar  curvature  of 
the  column  as  a  whole,  it  is  frequently  difficult  to  secure 
plates  depicting  the  vertebra  with  sufficient  accuracy  for 
diagnostic  purposes,  and  unless  great  care  is  taken  to  fol- 
low a  definite  procedure,  information  can  hardly  be  secured 
by  comparison  of  plates. 

Fig.  144  shows  an  outline  of  the  spinal  column  with 
its  common  divisions  into  cervical,  thoracic  and  lumbar. 
The  lateral  view  clearly  indicates  the  necessary  superposi- 
tion of  shadows,  and  it  can  be  readily  seen  how  slight  modi- 
fications in  position  may  result  in  very  considerable  defor- 
mation of  shadow  outline.  Possibly  the  best  general  rule 
would  be  that  the  central  portion  of  the  beam  used  should 
be,  as  near  as  possible,  perpendicular  to  the  spinal  column, 
and  in  all  cases  the  target  must  be  symmetrically  placed 
over  the  spine. 

Attention  must  also  be  called  to  the  fact  that  the  patient 
should  be  moved  and  handled  as  little  as  possible  and  al- 
ways with  extreme  care,  as  not  only  are  these  spinal  injuries 
likely  to  be  extremely  painful,  but  careless  handling  is  very 
likely  to  bring  about  injury  to  the  cord  even  if  this  were 
not  present  before  examination. 

Most  of  the  examinations  are  made  in  the  supine  posi- 
tion, and  it  is  essential  to  have  the  plate  or  film  come  as 
nearly  as  possible  in  contact  with  the  body  so  as  to  avoid 
distortion  and  hazing  of  the  shadow  by  reason  of  distance 
of  the  spine  from  the  plate.    In  some  cases  it  will  be  neces- 


314 


U.  S.  AR^IY  X-RAY  MANUAL 


sary  to  turn  the  patient  on  the  side  or  partially  so  for 
lateral  examination,  in  which  ease  sj^ecial  care  will  be 
needed. 


Fig.  144.  The  normal  spine  has  general  divisions  into  cervical, 
thoracic  and  lumbar.  The  projection  lines  from  targets  do  not  rep- 
resent standard  positions,  but  simply  illustrate  the  projection,  if  the 
central  rays  are  perpendicular  to  spinal  column.  The  operator  can 
vary  opening  of  cone,  size  of  plate  and  position  so  as  to  bring  out 
special  features  desired. 


i^^ractures  of  the  spine  may  be  simple  or  compound,  due 
to  either  direct  or  indirect  violence.  The  most  common 
is  the  compression  fracture  of  the  body  of  the  vertebrae, 


BONES  AND  JOINTS  315 

which  occurs  more  frequently  in  the  lower  thoracic  and 
upper  lumbar  reg:ions.  It  may  also  be  seen  in  the  mid- 
cervicals.  In  a  large  percentage  of  this  type  of  fracture 
there  is  an  associated  dislocation,  the  displacement  in  the 
cervicals  being  anteroposterior,  while  the  thoracic  and  lum- 
bar are  more  frequently  displaced  laterally. 

Transverse  or  spinous  processes  may  be  fractured  either 
by  direct  violence  or  by  muscular  action.  This  class  of 
injuries  is  usually  caused  by  forcible  bending,  as  in  ex- 
treme flexion,  resulting  from  a  fall.  These  fractures  may 
involve  one  or  more  vertebrae;  the  bodies  are  somewhat 
flattened  longitudinally  and  usually  show  a  wedge-shaped 
formation.  In  certain  cases  there  is  a  true  splintering 
of  the  bone  instead  of  crushing  of  the  body,  and  in  these 
cases  there  is  great  danger  of  injury  to  the  cord,  due  to 
the  action  of  bony  fragments. 

As  a  general  rule  no  preparation  of  the  patient  is  re- 
quired excepting  in  the  case  of  the  lower  thoracic  and 
lumbar  vertebrae,  in  which  case  a  thorough  cleansing  by 
cathartic  is  desirable. 

It  is  always  well  to  make  stereoscopic  plates  when  in 
doubt,  and  in  this  case  some  variation  in  the  time  of  ex- 
posure of  the  two  plates  may  be  of  advantage. 

The  following  brief  summary  of  the  positions  and  ex- 
posures is  given  and  it  is  suggested  that  the  roentgenologist 
who  has  not  had  experience  in  this  work  undertake  to 
make  plates  in  these  positions  with  normal  subjects,  when 
time  permits,  so  as  to  more  fully  understand  the  work  and 
be  able  to  carry  it  out  with  the  least  amount  of  disturbance 
to  the  patient. 

Upper  Cervicals.— Fig.  145.  The  head  should  be  sup- 
ported by  the  wooden  wedge  used  in  frontal  sinus  work, 
or  otherwise,  the  head  being  semiflexed.  The  mouth  may 
be  held  open  by  a  large  cork,  placed  as  far  back  between 


316 


U.  S.  ARMY  X-RAY  MANUAL 


the  molars  on  one  side  as  possible.  Care  should  be  taken 
to  fix  the  head  in  position  and  the  central  ray  should  be 
perpendicular  to  the  plate,  passing  directly  through  the 
open  mouth.  A  distance  of  22  inches  will  be  found  de- 
sirable and  an  approximate  exposure,   at  40  ma.,   5-inch 


Fig.    145.     Spine  examination,  anteroposterior  position  for   upper 
cervical  vertebras. 


gap,  of  from  3  to  5  seconds,  with  the  usual  base  hospital 
outfit. 

Lower  Cervicals. — Fig.  146.  The  ventrodorsal  projec- 
tion of  the  lower  cervicals  is  best  obtained  by  supporting 
the  plate  or  film  beneath  the  patient  at  such  an  angle  as  to 
bring  it  in  contact  with  the  region  sought.  In  this  case, 
also,  it  will  be  necessary  to  fix  the  head  in  position  to  avoid 
hazing  of  the  plate  by  movement.  Exposure  40  ma., 
5-inch  gap,  22-inch  target-plate  distance,  3  to  5  seconds. 


BONES  AND  JOINTS 


317 


Fig.  146.     Spine    examination,    anteroposterior    position    for    lower 
cervical  vertebrae. 


Fig.  147.     Spine  examination,  lateral  position  for  examination  of 
cervical  vertebrae. 


318 


U.  S.  ARMY  X-RAY  MANUAL 


If  a  lateral  view  is  desired,  the  patient  should  not  be 
turned  on  his  side  in  the  case  of  injury  to  the  cervical 
vertebrae,  but  a  plate  pressed  well  down  against  the  shoul- 
der and  properly  supported  by  sand-bags  or  otherwise  may 
be  used.  Fig.  147.  For  a  lateral  examination  it  is  well  to 
have  the  shoulders  slightly  elevated  and  to  be  sure  that 


Fig.  148.     Spine    examination,    anteroposterior    position    for    tho- 
racic vertebrae. 


the  plate  covers  the  region  sought.  It  may  be  necessary 
to  work  at  28  inches,  in  which  case,  with  40  ma.  and  a 
5-inch  gap,  5  to  7  seconds  may  be  needed. 

Thoracic  Vertebrae. — The  thoracic  vertebras  may  be 
taken  on  a  large  plate  with  a  target-plate  distance  of  28 
inches,  or  by  the  use  of  two  small  plates  and  two  separate 
exposures.     Fig.  148.     The  latter  is  generally  more  satis- 


BONES  AND  JOINTS 


319 


Fig.  149.     Spine  examination,  position  for  lateral  examination  of 
thoracic  vertebra. 


Fig.  150.     Spine    examination,   anteroposterior   position   for   upper 
lumbar  region.     Note  flexion  of  knees. 


320  U.  S.  ARMY  X-RAY  MANUAL 

factory.  With  40  ma.,  a  5-inch  gap,  28-inch  target-plate 
distance,  the  time  required  will  be  from  5  to  8  seconds. 
The  proper  plate  density  requires  careful  attention,  on 
account  of  the  mass  of  superimposed  material  that  must 
be  penetrated. 

The  position  for  lateral  examination  is  shown  in  Fig. 
149,  and  will  generally  require  somewhat  longer  exposure 
than  the  ventrodorsal,  running  from  6  to  10  seconds  with 
the  same  current,  gap  and  distance  as  before. 

Upper  Lumbar  Region. — On  account  of  the  considerable 
curvature  of  the  midlumbars  special  care  should  be  taken 
in  placing  the  tube  and  patient  in  order  to  bring  out  the 
positions  of  the  vertebrae  without  overlapping.  The  pa- 
tient should  lie  flat  on  the  back  and  the  knees  should  be 
semiflexed  in  order  to  bring  the  spine  as  close  to  the  plate 
as  possible.  The  central  ray  should  pass  through  the  12th 
thoracic  vertebra  approximately,  and  in  some  cases  a  cone 
for  compression  will  be  found  desirable  in  order  to  dimin- 
ish the  path  of  the  rays  in  the  body.  Fig.  150.  At  40 
ma.,  5-inch  gap,  22  inches  will  require  from  6  to  8  seconds. 

Positions  for  other  portions  of  the  lower  spine  are  indi- 
cated in  Figs.  151  and  152  and  require  some  practice  in 
order  to  bring  out  the  features  desired.  If  a  lateral  is 
required  of  the  lower  spine,  it  will  generally  be  desirable 
to  use  an  intensifying  screen,  and,  if  this  is  reasonably 
fast,  the  time  for  the  lateral  exposure  with  the  screen  will 
not  differ  materially  from  that  for  the  anteroposterior  when 
no  screen  is  used. 

Abnormalities  of  the  Spine. — Before  discussing  the  pa- 
thological changes  in  the  spine  it  is  well  to  remember 
that  it  is  the  seat  of  more  abnormalities  than  any  other 
part  of  the  bony  structure.  Certain  of  these  abnormali- 
ties while  not  pathological  in  the  sense  of  disease  yet  may 


BONES  AND  JOINTS 


321 


m 


:\ 


-"  I  -^r  ^HD= 


1  Y^^ 


.X  g^^_   ^_  ^^ 


Fig.  151.     Spine  examination,  lateral  position  for  lumbar  vertebrae. 


«^ 


.-..V.  '-'•'•■  t%-- 


PiG.  152,     Spine  examination,    anteroposterior   position   for   lower 
humbar  vertebrae. 


322  U.  S.  ARMY  X-RAY  MANUAL 

produce  symptoms.  For  convenience  it  is  well  to  con- 
sider them  according  to  their  locations,  namely,  cervical, 
dorsal,  and  lumbosacral. 

In  the  cervical  region  the  most  common  abnormality  is 
the  presence  of  extra  ribs.  They  generally  spring  from 
the  seventh  cervical;  may  be  either  unilateral  or  bilateral, 
the  former  being  the  most  common.  They  frequently  pro- 
duce pain  and  numbness  in  the  arm  and  sometimes  atrophy 
of  certain  muscles.  The  symptoms  usually  lead  to  a  diag- 
nosis of  neuritis  which,  if  due  to  pressure  from  one  of  these 
ribs,  will  not  yield  to  medical  treatment,  as  removal  of  the 
ribs  is  the  only  cure.  When  unilateral  the  diagnosis  is 
easy,  as  one  will  note  that  the  corresponding  rib  on  the 
opposite  side  is  absent.  When  there  are  two  cervical  ribs 
the  diagnosis  is  more  difficult,  as  they  may  be  mistaken 
for  the  pair  of  normal  first  dorsal  ribs.  This  can  be  deter- 
mined only  by  examination  of  the  entire  dorsal  spine  to 
ascertain  whether  twelve  or  thirteen  pairs  of  ribs  are  pres- 
ent. If  there  are  thirteen,  we  know  we  are  dealing  with 
an  extra  pair  of  cervical  ribs.  The  seventh  cervical  ver- 
tebra, from  the  radiological  appearance,  is  so  similar  to 
the  first  dorsal  that  no  conclusions  can  be  drawn  as  to 
whether  the  ribs  arise  from  the  seventh  cervical  or  first 
dorsal  vertebra.  The  fact  that  there  may  be  six  cervical 
vertebrae  does  not  mean  that  we  are  dealing  with  an  extra 
pair  of  ribs,  as  the  attachment  of  the  ribs  is  variable. 
Sometimes  they  are  attached  one  vertebra  too  high  or  one 
vertebra  too  low.  It  is  quite  common  to  find  six  cervical, 
twelve  dorsal  and  six  lumbar  vertebrae,  or  eight  cervical, 
twelve  dorsal  and  four  lumbar  vertebrae. 

While  these  extra  ribs  nearly  always  spring  from  the 
seventh  cervical  vertebra,  it  is  well  to  remember  that  on 
very  rare  occasions  they  may  be  attached  higher  up. 


BONES  AND  JOINTS  323 

Congenital  nonunion  of  the  laminae  that  form  the  spinous 
processes  is  quite  common  in  the  seventh  cervical.  On 
account  of  the  narrow  space  between  the  laminae  this  is 
often  mistaken  for  a  fracture. 

In  the  dorsal  vertebra?  we  may  also  have  congenital  non- 
union of  the  laminae,  generally  confined  to  the  upper  two 
or  three.  Rudimentary  vertebrae,  triangular  in  shape,  are 
sometimes  seen  inserted  between  the  vertebrae.  Since  they 
are  triangular  in  shape  and  inserted  on  one  side,  scoliosis 
invariably  results.  This  is  important,  as  such  a  condition 
will  not  yield  to  the  ordinary  treatment  for  scoliosis. 

In  the  lumbosacral  region  nearly  all  of  our  abnormali- 
ties are  confined  to  the  fifth  lumbar  and  sacrum.  Con- 
genital nonunion  of  the  lamina  of  the  fifth  lumbar  and 
top  of  the  sacrum  is  quite  common.  In  a  thousand  examina- 
tions of  that  region  for  various  conditions  this  nonunion 
occurred  in  over  fifteen  per  cent  of  the  cases.  This  is 
dwelt  upon  because  the  writer  has  seen  so  many  cases  in 
which  this  condition  was  diagnosed  as  fracture.  Occasion- 
ally an  extra  pair  of  ribs  may  arise  from  the  first  lumbar. 

Another  frequent  abnormality  is  where  the  fifth  lumbar 
takes  on  characteristics  of  the  sacrum — the  transverse 
processes  on  one  or  both  sides  become  fused  with  the  sacrum 
and  the  fifth  lumbar  becomes  integral  therewith.  When 
only  one  side  is  united  symptoms  frequently  occur. 

The  so-called  sacro-iliac  subluxation  or  strain  seems  to 
be  in  reality  a  ligamentous  rather  than  a  bony  change. 
In  such  conditions  one  will  frequently  see  one  side  of  the 
sacrum  higher  than  the  other,  suggesting  a  slipping.  When 
the  patient  is  manipulated  under  anesthesia  all  symp- 
toms may  disappear,  and  second  examination  fails  to  show 
that  the  improvement  has  resulted  from  any  change  in  the 
position  of  the  sacrum. 


324  U.  S.  ARMY  X-RAY  IMANUAL 

Great  care  must  be  taken  in  centering  the  tube  to  secure 
a  symmetrical  position  in  this  examination,  and  if  conclu- 
sions are  to  be  drawn  from  a  second  examination  as  re- 
gards the  effect  of  treatment  or  manipulation,  it  is  of  vital 
importance  to  reproduce  all  the  factors  of  position  and  ex- 
posure, in  order  that  distortion  may  not  be  mistaken  for 
real  change  in  bony  structure.  It  is  advised  that  the  tube 
be  centered  over  the  lumbosacral  articulation. 

While  many  of  these  cases  of  indefinite  pain  and  dis- 
comfort in  this  region  may  be  due  to  ligamentous  rather 
than  bony  changes,  it  must  be  borne  in  mind  that  we  do 
have  at  times  a  slipping  of  the  fifth  lumbar  vertebra.  A 
lateral  view  of  the  fifth  lumbar  and  top  of  the  sacrum  may 
show  the  body  of  the  fifth  lumbar  projecting  anterior  to 
the  top  of  the  sacrum. 

Pathological  Processes  in  the  Spine. — In  dealing  with 
the  pathological  processes  incident  to  the  spine  we  have 
practically  the  same  changes  as  seen  in  the  other  bones 
with  certain  modifications.  For  convenience  of  classifica- 
tion the  writer  has  divided  the  lesions  according  to  their 
origin  as  follows : 

1.  Joint  lesions.  Lesions  arising  from  and  involving  the 
articulating  surfaces. 

2.  Transitional  lesions.  Lesions  arising  from  the  articu- 
lating surfaces  and  involving  the  body  of  the  vertebrge. 

3.  Bone  lesions.  Lesions  arising  from  the  body  and  not 
involving  the  articulating  surfaces. 

In  class  one  will  fall  the  various  types  of  arthritis,  name- 
ly, infectious,  atrophic  and  hypertrophic,  and  the  first 
stage  of  tuberculosis. 

In  class  two  we  have  the  destructive  stage  of  tubercu- 
losis, fractures,  and  the  neuropathic  conditions  such  as 
Charcot  and  syringomyelia. 

In  class  three  we  have  the  new  growths  and  occasionally 


BONES  AND  JOINTS  325 

osteomyelitis,  though  this  may  come  under  class  two,  ac- 
cording to  whether  the  joint  is  involved  or  not. 

Spinal  Joint  Lesions. — In  dealing  with  class  one,  the  joint 
infections,  certain  changes  seen  in  the  joints  of  long  bones 
are  not  present,  that  is,  we  do  not  see  any  peri-articular  or 
fluid  changes,  so  our  diagnostic  points  rest  entirely  upon 
the  cartilaginous  destruction  and  bone  production. 

In  the  arthritic  cases,  nontuberculous,  we  seldom  see  any 
narrowing  of  the  joint  space,  but  at  the  edges  of  the  ver- 
tebra?, particularly  where  the  lateral  ligaments  attach,  the 
edge  will  first  become  sharpened  and  then  exostoses  will 
form,  growing  toward  the  joint  space,  and  finally  will  unite 
with  the  exostoses  from  the  other  surface  of  the  joint  and 
produce  a  true  bony  ankylosis  at  that  point.  This  may  be 
so  extensive  that  all  the  vertebra  will  become  ankylosed. 
There  is  no  change  in  the  body  of  the  vertebrte.  AYe  can- 
not differentiate  the  various  types  of  arthritis.  In  the  early 
stages  of  tuberculosis  we  get  destruction  of  cartilage  and 
some  narrowing  of  the  joint,  but  the  disease  proceeds  to 
attack  the  body  of  the  vertebra  and  then  we  get  the  second 
class,  or  the  transitional  type,  where  joint  and  body  are 
involved. 

Transitional  Spinal  Lesio7is. — In  tuberculosis  the  anterior 
portion  of  the  body  of  the  vertebra  becomes  softened  and 
then  from  pressure  gives  way,  assuming  a  characteristic  ap- 
pearance, namely,  the  body  becomes  triangular  in  shape 
with  the  apex  anterior  and  the  base  of  the  triangle  poste- 
rior. This  gives  us  the  characteristic  angulation  or 
knuckle,  the  true  tuberculous  kyphosis.  Tuberculosis  is  a 
destructive  process,  not  a  bone  producer.  The  three  im- 
portant differential  points  to  remember  with  this  lesion  are 
(1)  angulation;  (2)  deformity,  anterior  and  posterior;  (3) 
practically  no  bone  production. 


326  U.  S.  ARMY  X-RAY  MANUAL 

In  fracture  and  dislocation  of  the  spine,  and  they  are 
generally  present  together,  we  have  destruction  of  the  joint 
and  more  or  less  crushing  of  the  vertebras.  The  displace- 
ment is  lateral  and  soon  there  is  marked  new  bone  forma- 
tion. The  three  important  differential  points  are  (1) 
angulation;  (2)  deformity,  lateral;  (3)  new  formation  of 
bone. 

The  above  applies  only  to  the  dorsolumbar  region.  In 
the  cervical  region  in  fracture  and  dislocation,  the  dis- 
placement is  frequently  anteroposterior  instead  of  lateral, 
though  both  may  occur.  Besides  the  fracture-dislocation 
of  the  bodies  proper,  fracture  of  the  transverse  processes 
in  the  lumbar  region  is  quite  common.  These  not  only 
follow  from  injury  but  from  violent  strains.  They  are 
generally  easily  recognized,  as  there  is  always  more  or  less 
separation  of  the  fragments  and  the  outer  end  is  frequently 
displaced  upward. 

In  the  neuropathic  conditions,  namely,  Charcot,  there  is 
always  the  lateral  crushing  of  the  joint,  and  the  body  is 
involved  with  the  formation  of  bony  detritus,  seldom  new 
bone  formation.  The  three  differential  points  are  (1)  an- 
gulation; (2)  deformity,  lateral;  (3)  seldom  new  bone  for- 
mation, bu,t  generally  bony  detritus  present. 

Spinal  Bone  Lesions. — The  most  common  lesions  are  the 
new  growths,  and  the  same  system  of  differentiation  applies 
here  as  in  growths  of  the  long  bones.  When  the  growth 
arises  from  the  edge  of  the  vertebra  and  there  is  bone  pro- 
duction outside,  the  condition  may  simulate  fracture  and 
dislocation,  but  the  striking  point  is  that  in  growths  the 
joint  is  not  involved. 

In  sarcoma  and  carcinoma  a  portion  of  the  vertebra  may 
be  completely  absorbed,  but,  on  account  of  the  density  of 
the  growth,  crushing  of  the  body  takes  place  slowly  and 


BONES  AND  JOINTS  327 

equally.  The  body  will  become  narrowed,  but  the  joint 
spaces  will  be  intact  and  clearly  seen. 

A  vertebra  that  is  much  smaller  in  width  with  joint 
spaces  intact  should  always  be  viewed  with  the  possibility 
of  growth  in  mind.  The  characteristic  points  are  (1)  no 
angulation;  (2)  no  displacement;  (3)  narrowing  of  body 
with  or  without  bone  production,  according  to  type  of 
tumor. 

Osteomyelitis  is  uncommon,  though  the  writer  has  seen 
one  case  of  typhoid  origin  involving  both  the  joint  and 
body.  The  changes  observed  were  the  same  as  seen  in 
osteomyelitis  of  the  long  bones. 

Lesions  of  the  Long  Bones. — In  discussing  the  patho- 
logical lesions  that  take  place  in  bones  w^e  must  remem- 
ber that  w^e  have  three  normal  constituents  to  deal 
with,  namely,  the  medullary  canal  and  its  contents,  the 
cortex,  and  the  periosteum.  From  an  x-ray  standpoint 
there  are  only  two  pathological  changes  that  take  place, 
namely,  bone  destruction  and  bone  production.  It  mat- 
ters not  ^vhat  the  nature  of  the  lesion  is,  one  or  both 
of  these  processes  are  present.  It  is  only  by  a  careful 
analysis  of  the  character  of  the  destruction  and  the 
character  of  the  bone  production  that  w^e  are  enabled 
to  differentiate  these  lesions.  The  most  important  thing  to 
determine  is  whether  we  are  dealing  with  a  malignant  or 
a  benign  condition.  If  that  point  can  be  determined,  we 
have  given  the  surgeon  or  clinician  all  the  information  that 
is  necessary.  It  is,  however,  better  if  we  can  go  further 
and  determine  the  exact  nature  of  the  lesion. 

In  taking  up  the  subject  of  tumors  of  bone  there  are 
certain  well-known  manifestations  which  are  fairly  char- 
acteristic of  certain  lesions.  By  studying  the  point  of 
origin  and  the  character  of  the  bone  changes  we  have  been 
led  to  formulate  a  rough  scheme  for  the  analysis  of  these 


328  U.  S.  ARMY  X-RAY  MANUAL 

various  bone  tumors.  We  have  taken  as  a  basis  four  car- 
dinal points  which  are  as  follows:  origin  of  the  tumor; 
presence  or  absence  of  bone  production;  the  condition  of 
the  cortex ;  and,  finally,  invasion.  At  first  glance  it  is  often 
impossible  to  determine  all  four  of  these  points,  but,  if 
we  can  establish  one  or  two  of  them,  they  frequently  lead 
to  the  correct  diagnosis. 

Discussing  these  four  points,  the  salient  features  are  as 
follows : 

Point  of  Origin. — By  that  we  mean  whether  the  growth 
arises  in  the  medullary  canal  or  springs  from  the  cortex 
or  periosteum.  If  this  point  can  be  determined  we  have 
established  one  point  of  differential  diagnosis.  All  tumors 
in  bone  must  be  either  primary  or  metastatic.  We  know, 
for  example,  since  there  is  no  epithelial  tissue  in  bone, 
that  if  we  have  a  carcinoma  it  must  enter  the  bone  by 
means  of  the  lymph  vessel  with  the  nutrient  artery,  and, 
consequently,  the  growth  must  start  in  the  medullary 
cavity.  Therefore,  if  we  can  establish  the  point  that  the 
growth  does  not  arise  in  the  medullary  cavity,  we  have 
ruled  out  carcinoma.  On  the  other  hand,  since  sarcoma  is 
of  connective-tissue  origin  it  can  be  either  primary  in  the 
medullary  canal  or  of  metastatic  origin.  We  know,  too, 
that  enchondromata  and  bone  cysts  may  also  arise  from 
the  medullary  cavity,  so  we  have  to  proceed  to  the  other 
cardinal  points  to  establish  a  differential  diagnosis. 

Bone  Production. — Bone  production  cannot  take  place 
in  either  carcinoma  or  in  the  round-cell,  spindle-cell  and 
giant-cell  sarcomata.  Consequently,  if  we  can  establish 
the  point  that  there  is  bone  production  within  the  tumor, 
the  above-mentioned  tumors  can  be  ruled  out.  That,  in 
turn,  will  again  limit  the  tumors  to  osteoma,  osteochon- 
droma,   periosteal    sarcoma,    osteosarcoma,    and    ossifying 


BONES  AND  JOINTS  329 

hematoma — the  latter  arising  beneath  the  periosteum  is 
very  frequently  mistaken  for  a  malignant  growth. 

Cortex. — For  further  differentiation  we  have  to  proceed 
to  the  third  cardinal  point,  namely,  the  cortex.  AYe  must 
determine  whether  the  cortex  is  present  or  absent,  and,  if 
present,  whether  it  is  expanded  in  a  spherical  or  longi- 
tudinal manner.  Secondly,  we  must  determine  whether  the 
growth  springs  from  the  cortex  or  periosteum.  If  we  can 
definitely  establish  that  a  grow^th  springs  from  the  cortex 
or  periosteum  it  must  be  a  bone-producing  tumor,  and  the 
character  of  the  bone  production  will  definitely  aid  us  in 
determining  the  nature  of  the  tumor. 

The  condition  of  the  cortex  is  also  a  very  important 
factor.  Experience  has  shown  us  that  benign  tumors  aris- 
ing in  the  medullary  canal  always  take  the  path  of  least 
resistance,  that  is,  they  have  a  tendency  to  grow  up  and 
down  the  shaft  in  the  medullary  canal  rather  than  towards 
the  cortex  of  the  bone.  The  pressure  from  the  growth, 
however,  causes  an  expansion  of  the  cortex,  but  the  expan- 
sion is  always  spindle-shaped  or  cj^indrical  and  the  cortex 
is  always  intact.  On  the  other  hand,  in  malignant  condi- 
tions the  growth  is  always  spherical  in  nature  and  extends 
equally  in  all  directions.  The  cortex  does  not  offer  any 
interference,  and  the  growth  sweeps  through  and  destroys 
it,  so  that  in  this  character  of  growth  the  cortex  is  absent, 
and  if  a  trace  of  it  remains  it  has  not  been  expanded. 
There  is  only  one  exception  to  this,  and  that  is  the  giant-cell 
sarcoma.  As  its  name  implies,  it  belongs  to  the  sarcoma- 
tous group,  but,  on  account  of  the  character  of  the  cell, 
metastasis  is  almost  impossible,  so  that  we  are  dealing  with 
practically  a  benign  condition.  It  is  a  very  slow  growing 
tumor,  but  it  grows  in  a  spherical  manner,  and  on  account 
of  its  slow  growth  the  cortex  is  expanded  in  all  directions 


330  U.  S.  ARMY  X-RAY  MANUAL 

but  is  not  destroyed.  The  growth,  too,  is  definitely  limited 
in  the  medullary  canal. 

Invasion. — The  fourth  point,  invasion,  is  frequently  the 
hardest  to  determine.  If,  however,  it  can  be  determined,  it 
is  the  most  important  of  all  points.  If  we  can  establish  defi- 
nitely that  the  growth  is  invasive,  by  that  meaning  infiltra- 
tion into  bone  and  soft  tissue,  we  have  in  reality  determined 
everything,  because  malignancy  depends  upon  invasion. 

After  determining  these  four  points  it  is  well  then  to 
take  up  what  might  be  termed  the  laws  of  probabilities. 
By  these  laws  we  mean  what  is  most  frequently  found 
when  the  age  and  the  sex  of  the  patient  are  taken  into 
consideration,  and  what  particular  bone  is  involved.  As  an 
example,  if  the  patient  is  a  female,  statistics  show  that 
carcinomata  of  the  breast  and  of  the  pelvic  organs  are  by 
far  the  most  common.  We  also  know  that  in  carcinomata 
of  the  breast  metastases  occur  most  frequently  in  the 
greater  trochanter,  the  spine,  ribs,  humeri  and  the  ilia.  In 
carcinoma  of  the  pelvic  organs  the  metastases  are  generally 
in  the  lumbar  spine.  In  the  male  we  know  that  carcinomata 
of  the  lip  and  tongue  and  of  the  genito-urinary  organs 
are  most  common.  With  the  lip  and  tongue,  if  metastases 
do  occur,  they  take  place  chiefly  in  the  mandible.  In 
carcinomata  of  the  genito-urinary  organs,  particularly 
the  prostate,  the  metastases  occur  in  the  pelvis  and  lumbar 
spine.  Thus  we  see  that  knowledge  of  the  sex  of  the 
patient  is  frequently  an  important  aid  to  diagnosis. 

A  second  application  of  the  law  of  probabilities,  namely, 
the  age  of  the  patient,  helps  us  very  materially.  In  the 
first  place,  since  carcinoma  of  the  bone  is  a  metastatic 
condition  we  must  always  look  elsewhere  for  the  primary 
growth.  Then,  too,  experience  has  taught  us  that  carci- 
noma is  unusual  in  the  young  individual,  but  is  essentially 
a  disease  of  middle  and  old  age.     On  the  other  hand,  sar- 


BONES  AND  JOINTS  331 

coma  may  occur  at  any  age.  In  diagnosing  a  tumor  in  a 
young  individual,  the  law  of  probabilities  indicates  that 
it  is  more  likely  to  be  a  sarcoma  than  carcinoma ;  in  an 
old  individual  it  may  be  either  a  sarcoma  or  a  carcinoma. 

The  particular  bone  involved  when  sarcoma  is  present 
does  not  help  us  because  sarcoma  may  be  primary  in  the 
bone  and,  consequently,  can  form  in  any  bone.  The  fol- 
lowing are  the  chief  characteristics  of  the  more  common 
bone  tumors : 

Specific  Lesions. — Carcinoma  is  always  medullary  in 
origin  and,  since  it  enters  by  means  of  the  lymph  vessels, 
it  must  enter  the  bone  with  the  nutrient  artery,  that  is, 
at  its  middle  point.  Consequently,  we  may  say  by  the 
law  of  probabilities  that  carcinoma  is  more  apt  to  be  sit- 
uated in  the  region  where  the  nutrient  artery  enters. 
Since  it  is  epithelial  in  origin,  there  is  no  bone  produc- 
tion within  the  tumor;  it  grows  equally  in  all  directions, 
does  not  expand  the  cortex  but  destroys  it  completely, 
and  shows  distinct  signs  of  invasion  dow^n  in  the  med- 
ullary cavity  and  soft  tissues.  This  tumor  occurs  in  mid- 
dle and  old  age. 

Bound-cell  sarcoma  is  also  very  malignant  and  its  char- 
acteristics are  identically  the  same  as  those  of  carcinoma. 
As  far  as  the  growth  is  concerned  it  cannot  be  differentiated 
from  carcinoma  upon  the  x-ray  plate.  In  such  a  growth, 
to  make  a  differential  diagnosis  between  it  and  carcinoma, 
we  must  again  refer  to  the  law  of  probabilities,  namely, 
sex,  age  and  bones  involved.  Its  situation  in  the  bone  itself 
is  of  some  significance  because,  while  sarcoma  may  occur 
in  any  part  of  the  bone,  carcinoma  is  most  frequent  near 
the  nutrient  arterj^ ;  so  a  tumor  at  the  end  of  bones,  by  the 
law  of  probabilities,  is  more  apt  to  be  a  sarcoma  than 
carcinoma. 

Spindle-cell  sarcoma  while  malignant  is  not  as  much  so 


332  U.  S.  ARMY  X-RAY  MANUAL 

as  round-cell  sarcoma.  It  also  destroys  equally  in  all  direc- 
tions ;  does  not  produce  any  bone ;  destroys  the  cortex, 
does  not  expand  it;  but  the  growth  does  not  show  the 
same  degree  of  invasion  in  the  medullary  canal  as  the 
more  malignant  round-cell  sarcoma. 

Periosteal  sarcoma,  as  its  name  implies,  arises  from  the 
periosteum.  It  produces  bone,  but  the  major  portion  of 
the  bone  is  laid  down  in  the  soft  tissues.  The  shaft  of 
the  bone  shows  but  very  little  destruction.  This  tumor 
is  so  malignant  that  death  ensues  before  the  growth  has 
destroyed  the  bone  to  any  extent,  as  most  of  its  growth 
extends  into  the  soft  tissues.  The  bony  production  is  very 
typical  and  characteristic,  namely,  it  is  laid  down  in  long 
stria  and  is  invariably  perpendicular  to  the  shaft. 

Osteosarcoma  arises  from  the  cortex  of  the  bone.  It  is 
frequently  impossible  to  determine  whether  it  arises  from 
the  medullary  canal  or  not.  If  the  growth  should  start 
on  the  inner  surface  of  the  cortex  next  to  the  medullary 
canal,  since  it  grows  equally  in  all  directions,  one  might 
think  that  it  arose  from  the  medullary  canal.  So  the  point 
of  origin  in  some  of  these  cases  does  not  help  us,  but  the 
fact  that  there  is  bone  production  within  the  growth  is 
of  great  significance.  The  shaft  of  the  bone  is  somewhat 
destroyed  and  there  is  new  bone  production,  not  only  within 
the  shaft  but,  like  the  periosteal  sarcoma,  within  the  soft 
tissues.  This  bone,  like  the  periosteal  sarcoma,  is  laid  down 
perpendicular  to  the  shaft,  and  in  osteosarcoma  there  is 
generally  more  bone  production  than  in  the  periosteal  type. 
The  sarcomata  may  occur  at  any  age.  The  fact  that  in 
both  of  these  malignant  conditions  the  bone  is  laid  down 
perpendicularly  to  the  shaft  is  of  special  significance  and 
will  be  discussed  a  little  later. 

The  metastases  in  prostatic  carcinoma  give  the  same 
x-ray  signs  as  the  other  forms  of  carcinoma  with  this  ex- 


BOXES  AND  JOINTS  333 

ception.  Since  this  type  of  tumor  grows  very  slowly  we 
find  production  of  new  bone  not  within  the  growth  but 
just  at  the  edge  of  the  growth  in  the  normal  bone,  in  other 
words,  at  the  point  of  stimulation.  Consequently,  this 
growth  seems  to  be  encapsulated  in  a  calcium  wall,  nature 
attempting  to  limit  the  growth.  These  metastases  are  most 
commonly  seen  in  the  pelvic  bones,  sacrum  and  lower 
lumbar  vertebrae;  and  in  people  of  middle  or  old  age. 

Giant-cell  sarcoma  develops  from  the  medullary  portion 
of  the  bone  and  expands  equally  in  all  directions,  similar 
to  a  malignant  grow^th.  It  is,  however,  definitely  limited; 
the  cortex  is  expanded  but  intact.  There  is  no  new  bone 
formation.  It  is  generally  seen  between  the  ages  of  twenty 
and  thirty.  The  growth  is  usually  situated  at  the  end  of 
the  bone,  and  the  radius  and  tibia  seem  to  be  the  bones 
most  commonly  involved. 

Enchondroma,  as  its  name  implies,  is  cartilaginous  in 
origin  and  is  generally  seen  before  the  epiphyses  have 
united.  The  early  recognition  is  probably  due  to  the  fact 
that  fractures  take  place  through  this  growth  quite  readily ; 
the  patient  comes  in  for  the  fracture  and  the  tumor  is  then 
discovered.  The  growth  is  situated  near  the  ends  of  the 
bones  in  the  region  of  the  epiphyseal  line,  seldom  extend- 
ing beyond  this  line  into  the  epiphysis  proper.  It  is  gen- 
erally multiple  and  the  growth  is  cystic  in  character — 
one  growth  may  contain  several  cystlike  formations.  It 
extends  up  and  down  the  shaft;  the  cortex  is  expanded  in 
a  spindle-shaped  manner  but  intact.  There  is  no  new  bone 
formation  unless  there  has  been  an  injury.  It  may  arise 
either  from  the  medullary  portion  or  the  cortex.  Any  of 
the  long  bones  in  the  body  may  be  involved,  the  phalanges 
of  the  hands  being  probably  the  most  common.  These  us- 
ually occur  between  the  ages  of  seven  and  fifteen  years. 

A  cyst  is  seen  most  commonly  in  the  same  ages  as  the 


334  U.  S.  ARMY  X-RAY  MANUAL 

enchondroma  and,  like  it,  occurs  at  the  ends  of  the  bones 
in  the  region  of  the  epiphyseal  line.  It  extends  up  and 
down  the  shaft ;  the  cortex  is  expanded  in  a  spindle  shape ; 
the  cyst  may  be  lobulated,  but  is  generally  one  large  single 
cavity;  the  cortex  is  intact  and  the  walls  of  the  cyst  are 
sharply  defined.  Cysts  are  supposed  to  be  multiple,  but 
in  a  great  number  of  cases  observed  by  the  writer  no  case 
of  multiple  cysts  was  found.  Cysts  are  generally  medullary 
in  origin  and  occasionally,  but  rarely,  may  spring  from 
the  cortex. 

Osteoma  arises  from  the  cortex  and,  as  its  name  implies, 
is  a  dense  bony  tumor.  The  growth  extends  out  into  the 
soft  tissues,  the  bone  being  laid  down  very  symmetrically, 
and  has  the  typical  cauliflower  appearance.  It  is  fre- 
quently lobulated,  has  a  very  definite  outline,  and  no  sign 
of  invasion.  These  growths  are  generally  multiple  at  the 
point  of  origin,  are  seen  most  commonly  in  the  young,  and 
are  generally  perpendicular  to  the  shaft.  The  bone  in  these 
growths  is  much  denser  than  the  shaft  and  does  not  have 
the  same  bony  structure.  Exostoses  are  sometimes  mis- 
taken for  small  osteomata.  Exostoses,  however,  have  the 
same  character  of  bone  formation  as  the  shaft ;  they  spring 
from  the  shaft  at  an  angle  and  always  point  away  from 
the  nearest  epiphysis.  Occasionally  one  may  see  such  an 
exostosis  with  an  osteoma  forming  at  the  tip.  The  most 
common  situation  for  osteomata  is  around  the  shoulder  and 
in  the  neighborhood  of  the  knee  joint. 

Ossifying  kematomata,  while  quite  common,  are  at  the 
same  time  often  mistaken  for  malignant  growths  clinically. 
The  x-ray  appearance,  however,  is  quite  different.  This 
lesion  is  caused  by  some  trauma  to  the  periosteum  which 
causes  the  formation  of  a  hemorrhage  beneath  the  perios- 
teum and  it,  in  turn,  is  raised  up  by  the  hemorrhage.  When 
this  first  takes  place  the  x-ray  appearance  does  not  help 


BONES  AND  JOINTS  335 

us,  as  it  reveals  nothing,  but  at  the  end  of  about  three 
weeks  the  periosteum  wiii  lay  down  new  bone  and  the 
hemorrhage  beneath  it  will  undergo  organization  with  a 
deposition  of  calcium  salts.  The  calcium  salts,  however, 
are  laid  down  parallel  to  the  bone,  and  the  periosteum,  of 
course,  makes  a  definite  border  to  the  growth.  In  adult  life 
this  is  most  commonly  seen  in  the  thigh ;  in  children  it  may 
occur  in  any  bone  but  only  in  connection  with  scurvy. 

Special  attention  must  be  given  to  the  way  in  which  the 
new  bone  is  laid  down  in  this  condition.  "We  have  already 
spoken  of  four  conditions  in  which  bone  has  apparently 
been  thrown  down  in  the  soft  tissues:  two  malignant  con- 
ditions, periosteal  sarcoma  and  osteosarcoma ;  two  benign 
conditions,  osteoma  and  ossifying  hematoma.  The  impor- 
tant differential  point  is  that  in  malignant  conditions  the 
bone  is  laid  down  perpendicular  to  the  shaft  and  in  benign 
conditions  it  is  laid  down  parallel  to  the  shaft. 

Osteitis  fibrosa  cystica  is  occasionally  seen  and  can  easily 
be  classified  as  a  benign  condition  by  the  fact  that  the 
bone  has  become  softened  and  deformities  have  resulted, 
particularly^  around  the  head  of  the  femur.  The  shaft  is 
expanded  cylindrically,  the  cortex  is  intact  and  the  bone 
itself  is  frequently  filled  with  multiple  cystlike  formations. 
It  generally  occurs  in  the  young  adult. 

Paget' s  disease  is  sometimes  mistaken  for  osteomyelitis. 
It  is  seen  in  the  long  bones,  particularly  the  tibia  and 
femur,  and  the  cranial  bones  are  also  affected.  The  long 
bones  may  be  somewhat  bowed,  there  are  long  longitudinal 
strise  of  absorption  present  and  longitudinal  areas  of  in- 
creased calcium  salts.  The  cortex  in  places  may  be  thick- 
ened. The  changes  in  the  cranial  bones,  however,  are  most 
characteristic.  The  head  seems  to  be  enlarged,  and  the 
x-ray  appearance  shows  that  the  parietal,  frontal  and  occip- 
ital bones  are  very  much  thickened  by  knobbylike  deposits 


336  U.  S.  ARMY  X-RAY  MANUAL 

of  bone.  In  acromegaly  the  cranial  bones  are  very  much 
thickened ;  the  head  seems  to  be  elongated  anteroposteriorly 
and  the  lower  jaw  projects  markedly  forward.  The  sella 
turcica  is  frequently  enlarged  and  deepened.  The  bones 
and  soft  tissues  of  the  hands  and  feet  are  very  mu.ch 
enlarged,  and  the  tufting  of  the  terminal  phalanges  is 
materially  increased. 

Brain  Tumors. — In  speaking  of  the  changes  in  the 
cranial  bones  it  is  well  to  mention  in  this  connection  some 
of  the  characteristic  signs  of  brain  tumors.  Unfortunately, 
the  x-ray  evidence  for  these  tumors  is  not  particularly 
reliable,  as  a  vast  majority  of  brain  tumors  are  of  the 
same  consistency  as  the  brain  itself  and,  consequently, 
there  can  be  no  differentiation  between  the  tumor  and 
the  brain.  We  have  to  depend  entirely  upon  other  signs, 
and,  unfortunately,  they  are  late  manifestations  of  the 
tumor,  namely,  erosion  of  the  bone,  due  to  pressure,  and 
engorgement  of  the  vessels — these  vessels  having  a  tend-' 
ency  to  center  at  one  point,  that  is,  in  the  growth.  This 
indirect  evidence,  however,  cannot  always  be  relied  upon. 
In  tumors  of  the  hypophysis  the  signs  of  pressure  appear 
earlier.  Since  this  gland  is  closely  confined  in  the  sella 
turcica  the  pressure  symptoms,  such  as  erosion  and  dis- 
tortion of  the  bone,  appear  early. 

Osteomyelitis. — Care  must  be  taken  not  to  confuse  in- 
flammatory growths  of  bone  with  tumors.  This  is  par- 
ticularly true  in  osteomyelitis.  This  disease  gives  no  defi- 
nite x-ray  signs  during  the  early  stages  (first  ten  days). 
Later  we  find  destruction  within  the  bone  with  the  for- 
mation of  sequestra,  and  the  disease  extends  down  the 
shaft  in  an  irregular  manner,  but  the  shaft  is  never  ex- 
panded. The  periosteum  may  lay  down  new  bone  which 
may  give  the  appearance  of  expansion,  but  upon  looking 
at  the  plate  closely  we  will  see  that  the  apparent  expan- 


BONES  AND  JOINTS  337 

sion  is  clue  to  the  deposition  of  bone  on  the  outside.  When 
the  disease  breaks  through  the  cortex  it  does  so  in  one  or 
two  places  only  and  does  not  destroy  the  cortex  as  a  whole, 
as  the  malignant  tumors  do.  It  is  sometimes  quite  difficult 
to  differentiate  between  simple  osteomyelitis  and  that  oc- 
casioned by  lues.  It  is  well  to  bear  in  mind  that  when 
we  have,  apparently,  an  extensive  osteomyelitis  of  the  bone, 
very  little  swelling  of  the  soft  tissues,  and  very  few  clini- 
cal signs,  the  condition  is  more  apt  to  be  luetic  in  origin, 
as  the  acute  simple  inflammatory  osteomyelitis  is  generally 
accompanied  by  marked  clinical  signs  and  marked  soft 
tissue  swelling,  redness  and  fever. 

Periostitis  may  be  a  simple  inflammatory  lesion  or  luetic 
in  origin.  It  is  sometimes  very  difficult  to  differentiate 
these  two  conditions.  The  simple  inflammatory  periostitis 
lays  down  the  periosteal  bone  parallel  to  the  shaft.  Luetic 
periostitis  also  generally  lays  down  bone  parallel  to  the 
shaft,  but  occasionally  the  new  periosteal  bone  may  be 
laid  down  perpendicular  to  the  shaft  very  similar  to  that 
seen  in  certain  bony  malignancies.  In  the  luetic  periostitis, 
however,  the  amount  of  bone  is  small  and  closely  confined 
to  the  shaft,  not  extending  out  into  the  soft  tissues,  so 
that  a  mistake  can  probably  seldom  arise.  In  luetic  perios- 
titis more  than  one  bone  is  frequently  involved,  while  the 
simple  inflammatory  type  generally  affects  only  one  bone. 

The  cardinal  points  which  have  just  been  given  for  bone 
lesions  hold  only  for  the  long  bones  and  not  for  the  flat 
bones,  as  in  the  flat  bones  the  growth  is  so  frequently 
atypical.  A  second  important  point  to  remember  is,  that, 
if  there  has  been  any  surgical  interference,  no  conclu- 
sions can  be  drawn  from  the  x-ray  standpoint,  because 
the  diagnosis  depends  upon  bone  destruction  and  bone  pro- 
duction. If  there  has  been  trauma  or  surgical  interfer- 
ence the  new  bone  production  may  be  due  entirely  to  the 


338  U.  S.  ARMY  X-RAY  MANUAL 

two  latter  conditions.  Consequently,  we  may  draw  false 
conclusions,  since  these  changes  are  not  due  to  the  tumor 
itself. 

Tuberculosis  of  the  joints  with  direct  extension  of  the 
disease  into  the  heads  of  the  bone  forming  the  joint  has 
been  taken  up  in  the  section  on  arthritis.  Tuberculosis 
of  the  long  bones  without  the  joint  involvement  is  so  ex- 
tremely rare  that  it  does  not  come  within  the  scope  of  this 
manual. 

Below  is  a  summary  of  the  bone  tumors  according  to  the 
four  cardinal  points : 

1.  Origin-Medullary. 

Sarcoma 
Carcinoma 
Bone  cysts 
Enchondroma 
Giant-cell  sarcoma 

2.  Cortical. 

Periosteal  sarcoma 
Osteosarcoma 
Osteom.a 
Enchondroma 
Ossifying  hematoma 
Occasionally  bone  cysts 

3.  Bone  Production. 

Periosteal  sarcoma 
Osteosarcoma 
Osteoma 

Ossifying  hematoma 

Enchondroma  and  bone  cysts  (when  there  has  been 
trauma) 

4.  Cortex  not  expanded  but  destroyed. 

Sarcoma 


BONES  AND  JOINTS  339 

Carcinoma 
Osteosarcoma 
Periosteal  sarcoma 

5.  Cortex  expanded  and  intact. 

Enchondroma 
Bone  cysts 
Giant-cell  sarcoma 

6.  Invasion. 

All  of  the  malignant  tumors  show  invasion. 

Arthritis. — A  normal  joint  is  composed  of  three  parts, 
namely,  cartilage,  synovial  membrane  and  the  synovial 
fluid.  There  is  no  free  bone  in  the  joint  proper;  the  con- 
sequence is  that  in  attempting  diagnosis  of  joint  condi- 
tions we  do  so  by  means  of  the  changes  in  one  or  more 
of  these  three  parts. 

We  may  divide  arthritic  conditions  into  two  classes. 
First,  the  acute,  and,  second,  that  large  group  which  we 
may  class  as  arthritis  deformans.  Under  the  first  group 
would  come  the  acute  polyarticular  rheumatism.  This  type 
comes  nearer  to  being  a  distinct  clinical  entity  than  any 
of  the  other  forms  of  this  disease. 

The  object  of  this  article  is  not  to  deal  with  the  clinical 
symptoms  but  with  the  x-ray  findings ;  consequently,  we 
will  confine  ourselves  entirely  to  the  changes  that  can  be 
seen  upon  a  plate. 

In  acute  polyarticular  arthritis  the  x-ray  indications  are 
rather  indefinite.  AYe  find  that  there  is  an  increased 
amount  of  fluid  in  the  joint,  and  the  synovial  membrane 
and  periarticular  tissues  are  swollen.  There  is  no  de- 
struction of  cartilage,  as  we  can  tell  by  the  fact  that  the 
joint  space  is  of  normal  width.  The  cartilage  itself  is  not 
visible  by  means  of  the  x-ray,  so  w^e  have  to  judge  its 
presence  or  absence  by  indirect  evidence,  namely,  the  width 


340  U.  S.  ARMY  X-RAY  IMANUAL 

between  the  bony  surfaces  that  compose  the  joint.  Since, 
in  this  condition,  there  is  no  destruction  of  cartilage  we 
may  expect  the  joint  to  come  back  to  its  normal  condi- 
tion, and,  after  the  disease  has  subsided,  the  x-ray  examina- 
tion will  show  an  absolutely  normal  joint. 

When  we  take  up  conditions  in  rheumatoid  affections 
we  meet  very  considerable  difficulties.  The  classifications 
of  the  various  types  under  this  head  are  very  unsatis- 
factory, and  then,  too,  these  so-called  chronic  rheumatisms 
have  so  many  names  for  the  same  condition.  For  example, 
we  see  the  terms  chronic  rheumatism,  arthritis  deformans, 
rheumatoid  arthritis,  osteoarthritis  and  spondylitis  used 
indiscriminately  by  different  individuals  and  yet  meaning 
the  same  condition.  There  is  no  classification  which  is  ab- 
solutely satisfactory,  but  that  adopted  by  Goldthwaite 
many  years  ago  is,  taken  as  a  whole,  probably  the  best. 
Of  course,  many  men  take  exception  to  his  classification 
and  do  not  agree  with  it  as  a  whole,  but  its  simplicity  and 
the  great  number  of  cases  which  can  be  classified  accord- 
ing to  it  makes  it  seem  generally  the  most  useful.  He  di- 
vides the  chronic  arthritis  into : 

1.  The  infectious  type.  This  includes  tuberculosis, 
gonorrhea,  syphilis,  pneumococcic  infection  and  those 
types  of  arthritis  which  have  the  same  clinical  manifesta- 
tions, but  where  the  etiological  factor  is  unknown. 

2.  Those  cases  designated  as  atrophic. 

3.  The  hypertrophic  cases. 

Infectious  arthritis,  from  an  x-ray  standpoint,  presents 
three  different  appearances,  according  to  the  stage  of  the 
disease  at  the  time  of  examination.  For  example,  in  the 
first  stage  we  have  an  acutely  inflamed  joint,  and  a  marked 
amount  of  fluid  present  with  periarticular  swelling.  There 
is  no  cartilaginous  destruction  and  consequently  no  bone 
destruction.     This  stage  gives  the  same  x-ray  appearance 


BONES  AND  JOINTS  341 

as  an  acute  polyarticular  rheumatism  or  an  injury  to  the 
joint  without  fractupe,  because  in  these  conditions  we  also 
get  fluid,  periarticular  swelling  and  no  cartilaginous 
changes.  In  the  second  stage  the  disease  probably  reaches 
its  maximum  intensity  and,  in  time,  the  following  changes 
take  place  in  the  joint  and  bone.  In  the  first  place,  on 
account  of  the  disuse  of  the  joint,  we  begin  to  get  a  general- 
ized atrophy  of  the  bone,  the  sw^elling  has  partially  disap- 
peared and  the  fluid  may  be  partially  absorbed.  The 
cartilage  is  now  eroded,  as  shown  by  the  fact  that  the 
joint  space  is  narrowed,  but  there  is  no  new  bone  forma- 
tion. The  soft  tissues  may  have  even  atrophied  some- 
what. Occasionally  we  may  see  punched-out  areas  extend- 
ing through  the  cartilage  down  into  the  bone.  In  the  third 
stage,  or  we  may  term  it  the  stage  of  repair,  the  active 
infection  has  disappeared  and  the  patient  is  beginning  to 
use  the  joint,  consequently,  the  atrophy  is  disappearing  or 
will  have  completely  disappeared.  The  soft  tissues  are 
resuming  their  normal  appearance,  and,  where  the  cartilage 
has  been  destroyed,  it  is  replaced  by  proliferation  of  new 
bone.  In  other  words,  w^e  get  the  formation  of  bony  exos- 
toses. The  extent  of  these  exostoses  depends  entirely  upon 
the  severity  of  the  lesion,  and  in  some  cases  cartilage  has 
been  so  completely  destroyed  that  we  have  a  true  bony  anky- 
losis. This  type  of  infection  is  seen  in  all  ages  of  life, 
that  is,  from  early  adult  life  up  to  and  through  old  age. 
Atrophic  Arthritis. — Atrophic  arthritis  is  generally 
seen  in  early  middle  age.  There  is  marked  atrophy  of 
both  soft  tissues  and  bone.  The  joints  are  frequently  par- 
tially subluxated,  due  to  the  contraction  of  the  tendons, 
and  there  is  limitation  of  motion;  the  latter  is  not  due  to 
bony  ankylosis,  however,  but  to  fibrous  changes  and  muscle 
contracture.  The  x-ray  examination  shows  marked  atrophy 
of  the  bone.     There  is  extensive  absorption  of  cartilage 


342  U.  S.  ARMY  X-RAY  MANUAL 

and  its  complete  destruction  in  certain  areas,  but  there  is 
apparently  no  attempt  at  new  bone  formation.  From  this 
description  one  can  readily  see  that  the  atropic  arthritis 
simulates  very  closely  the  second  stage  of  infectious  ar- 
thritis. The  only  differential  point  is  that  at  no  stage  in 
this  disease  is  there  any  fluid  or  periarticular  swelling, 
while  in  the  second  stage  of  infectious  arthritis  one  is  apt 
to  find  a  small  remaining  amount  of  swelling  and  fluid. 
Many  clinicians  think  that  atrophic  arthritis  is  not  a  dis- 
tinct clinical  entity  but  probably  one  of  the  stages  in  an 
infectious  arthritis. 

Hypertrophic  Arthritis. — Hypertrophic  arthritis  is  a 
disease  almost  invariably  associated  with  people  of  middle 
life  and  old  age.  One  rarely  sees  this  type  under  thirty- 
five  and  it  is  most  pronounced  in  patients  in  the  neighbor- 
hood of  fifty  and  over.  The  x-ray  examination  shows  that 
there  is  practically  no  atrophy,  in  fact,  there  is  condensa- 
tion of  bone  so  that  the  bone  shadows  are  even  a  little 
denser  than  normal.  When  the  age  of  forty-five  is  reached 
there  is  always  a  certain  amount  of  atrophy  in  the  bone, 
due  to  what  might  be  called  a  senile  change.  This  is  com- 
pletely absent  in  the  hypertrophic  type.  Besides  the  con- 
densation of  bone  there  is  a  marked  formation  of  exostoses, 
due  to  small  areas  of  cartilaginous  destruction  and  marked 
lipping  at  the  edge  of  the  articulating  surfaces.  Fre- 
quently little,  bony,  loose  bodies  may  be  present  in  the 
joint  (joint  mice).  There  may  be  ankylosis  of  the  joint, 
but  this  is  not  a  true  bony  ankylosis  but  simply  one  due 
to  the  mechanical  locking  of  these  bony  exostoses.  This 
type  simulates  the  third  stage  or  the  stage  of  repair  in  an 
infectious  arthritis.  In  hypertrophic  arthritis,  if  the  con- 
densation of  bone  is  absent,  it  is  extremely  difficult  and, 
at  times,  impossible  to  differentiate  between  the  third  stage 


BOXES  AND  JOINTS  343 

of  infectious  arthritis  and  hypertrophic  arthritis,  particu- 
lar!}- if  the  patient  is  in  the  neighborhood  of  fifty. 

Great  care  must  be  taken  not  to  confuse  the  slight  ar- 
thritic changes  which  are  always  present  in  people  over 
fifty  with  an  acute  active  process.  It  has  been  definitely  es- 
tablished that  practically  all  of  us  wiien  we  reach  the  age 
of  forty-five  show  small  exostoses  in  and  around  the  joints, 
and  yet  there  may  be  no  clinical  manifestations  of  an 
arthritic  process.  It  is  particularly  in  these  joints  that 
we  get  such  marked  symptoms  following  a  slight  injury — 
symptoms  out  of  proportion  to  the  extent  of  the  injury. 
In  this  condition  we  must  remember  that  the  injury  has 
simply  lowered  the  resistance  of  the  joint  and  has  allowed 
this  quiescent  arthritis  to  flare  up  into  an  active  process, 
so  that  the  marked  clinical  manifestations  seen  in  such 
joints  are  really  the  result  of  the  arthritis  and  not  of  the 
trauma. 

We  have  mentioned  the  subdivisions  under  infectious 
arthritis  where  the  etiological  factor  is  known.  The  ques- 
tion naturally  arises,  do  any  of  these  give  such  definite 
x-ray  changes  that  we  can  actually  determine  the  specific 
type  of  the  infection  with  which  we  are  dealing.  Unfor- 
tunately, the  majority  of  them  give  the  same  x-ray  indi- 
cation. Some,  however,  give  fairly  constant  appearances 
so  that  they  can  be  readily  recognized. 

In  tuherculosis  of  the  joint  we  have  a  marked  hazing  so 
that  the  x-ray  shadows  are  very  indistinct.  In  fact,  it 
suggests  that  we  have  a  very  poor  plate,  but  in  this  same 
plate  one  wall  note  that  the  bones  adjacent  to  the  affected 
joint  come  out  sharply  and  distinctly.  It  is  only  the  joint 
itself  that  is  hazy  and  indistinct.  This  is  due  entirely  to 
the  thickening  of  the  synovial  membrane.  Upon  close  in- 
spection we  will  find  that  the  bone  contour,  that  is,  the  bone 
beneath   the   cartilage,    is   very   indistinct,    irregular    and 


344  U.  S.  ARMY  X-RAY  MANUAL 

eaten  out.  In  the  active  process  fluid  is  present  and  there 
is  marked  periarticular  thickening.  When  the  disease  sub- 
sides this  haziness  and  indistinctness  of  the  joint  disap- 
pears, but  we  still  have  an  irregular  and  eroded  joint  sur- 
face, indicating  that  there  has  been  some  destruction  of 
cartilage  and  slight  destruction  of  the  bone  beneath.  There 
is  very  little  tendency  to  new  bone  formation,  and  the 
ankylosis,  if  present,  is  generally  fibrous  in  nature.  Since 
these  joints  when  untreated  so  frequently  form  sinuses, 
there  is  a  great  chance  of  having  another  infection  besides 
the  tuberculosis  in  the  joint.  It  is  in  these  mixed  in- 
fections that  we  see  the  marked  new  bone  formation. 

Gonorrheal  arthritis  does  not  give  us  distinct  x-ray  ap- 
pearances. It  varies  according  to  the  severity  of  the  lesion. 
In  only  one  joint  do  we  have  fairly  definite  characteristics, 
namely,  the  knee  joint.  In  that  particular  joint,  for  some 
reason,  the  greatest  severity  of  the  lesion  seems  to  take 
place  in  the  cartilages  beneath  the  patella,  and  early  bony 
ankylosis  occurs.  In  a  knee  joint  in  which  we  find  anky- 
losis between  the  patella  and  the  femur  gonorrheal  arthritis 
must  be  borne  in  mind.  Exostoses  and  ankylosis  are  quite 
common  in  this  disease. 

Syphilitic  arthritis  shows  marked  periarticular  swelling, 
thickening  of  the  synovial  membrane  and  fluid  in  the  joint. 
This  type  does  not  go  on  to  cartilaginous  destruction,  con- 
sequently, when  the  disease  subsides  we  have  a  perfectly 
normal  joint.  The  x-ray  appearance  is  identically  the  same 
as  that  of  an  acute  polyarticular  rheumatism.  Fortunately, 
this  type  is  generally  accompanied  by  bone  change.  While 
this  change  is  not  present  in  the  joint  itself  at  the  same 
time  it  is  fairly  characteristic,  namely,  a  small  area  of 
periostitis  forming  just  at  the  point  where  the  cartilage  of 
the  joint  ceases  and  the  periosteum  of  the  bone  begins. 
This  periostitis  in  conjunction  with  periarticular  swelling 


BONES  AND  JOINTS  345 

and  fluid  in  the  joint  is  fairly  characteristic  of  a  syphilitic 
lesion. 

The  Charcot  Joint  must  not  be  confused  with  this  acute 
syphilitic  joint,  since  the  changes  in  the  former  are  neuro- 
pathic rather  than  infectious  and  are  characterized  by 
great  destruction  of  the  joint  with  splitting  off  of  large 
fragments  of  bone,  which  lie  free  in  a  swollen  joint  filled 
more  or  less  with  fluid.  In  addition,  there  is  marked 
eburnation  of  the  remaining  ends  of  the  bones.  Upon 
glancing  at  such  a  joint  one  is  struck  by  the  marked  de- 
gree of  disorganization  that  it  has  undergone  and  instinc- 
tively feels  that  such  a  joint  could  not  possibly  be  used. 
On  the  other  hand,  there  is  absolutely  no  atrophy  of  the 
bones,  indicating  that  the  joint  has  not  been  at  rest.  Joints 
which  undergo  any  degree  of  disorganization  are  always 
extremely  painful  and  remain  at  rest.  They  consequently 
show  marked  atrophy,  so  that  when  one  sees  a  markedly 
disorganized  joint  without  any  atrophy  of  the  bone  at  all 
one  should  seriously  consider  the  possibility  that  the  con- 
dition is  not  an  ordinary  infection  but  a  Charcot  joint. 

Occasionally,  but  not  frequently,  one  runs  across  a  joint 
giving  the  clinical  symptoms  of  an  infectious  arthritis,  but 
the  x-ray  examination  shows  a  rather  remarkable  condition. 
There  is  marked  destruction  of  the  cartilage  of  the  joint, 
slight  new  bone  formation,  and  a  hazy  joint,  simulating 
tuberculosis ;  but  in  the  joint  cavity  itself  there  is  a  blood 
clot  which  has  undergone  either  fibrous  or  bony  change. 
When  such  a  condition  is  present  it  is  invariably  the  result 
of  hemophilia. 

The  remaining  forms  of  infectious  arthritis  do  not  give 
any  definite  x-ray  appearances.  The  object  of  this  chapter 
is  to  give  a  rough  classification.  In  joint  diseases,  as  in 
other  conditions,  the  clinical  aspect  of  the  case  must  be 
taken  into  consideration  in  order  to  arrive  at  a  diagnosis. 


SINUSES   AND    MASTOIDS 

Technique  for  Mastoids. — It  is  necessary  to  make  an 
examination  of  both  mastoids.  Tliis  may  be  done  on  one 
8  by  10  plate,  by  covering  one-half  of  the  plate  with  a 
thick  piece  of  lead  and  making  one  exposure  on  the  un- 
covered portion,  then  changing  the  lead  cover  to  the  exposed 
side  and  making  the  second  exposure  on  the  side  which 
had  previously  been  covered.  It  is  necessary  to  compare 
one  mastoid  with  the  other,  and  placing  both  on  the  one 
plate  makes  comparison  of  the  two  sides  much  easier  than 
if  separate  plates  are  made. 

The  patient  lies  on  a  table  with  the  head  on  a  small 
raised  platform,  the  affected  ear  next  to  the  plate  with  the 
pinna  folded  forward.  There  should  be  a  clamp  on  the 
platform  with  adjustable  pads  to  press  on  the  occiput  and 
forehead,  but  not  so  as  to  obstruct  a  clear  view  of  the 
mastoid  cells.  The  head  is  placed  so  that  the  sagittal  plane 
will  be  parallel  to  the  plate.  The  tube  is  centered  over 
the  head  in  such  a  way  as  to  direct  the  central  ray  down- 
wards and  forwards  toward  the  opposite  ear.  An  angle 
of  fifteen  degrees  from  behind  forward  towards  the  face 
and  fifteen  degrees  from  above  downward  towards  the  feet 
will  in  the  majority  of  cases  be  correct.  In  case  the  shape 
of  the  head  is  such  that  the  sagittal  plane  cannot  be  placed 
parallel  with  the  plate,  without  raising  the  mastoid  area 
above  the  plate,  the  angle  of  the  tube  must  be  altered  to 
accommodate  it.  The  central  ray  should  enter  the  head 
above  and  behind  the  external  auditory  canal,  and  emerge 
at  the  external  auditory  meatus  next  to  the  platCv 

346 


SINUSES  AND  :\rASTOIl)S 


347 


fee 

OS   cp 


s  o 


o    ~ 


I—i      — 

cS  ho 


348  U.  S.  ARMY  X-RAY  MANUAL 

The  tube  stand  should  be  supplied  with  a  small  cone 
and  this  brought  down  with  firm  pressure  on  the  head. 
Stereoscopic  plates  may  be  made  by  shifting  and  tilting 
the  proper  distance  on  each  side  of  the  angle.  Figs.  153 
and  154. 

Technique  for  Accessory  Sinuses. — In  order  to  obtain  a 
satisfactory  postero-anterior  image  of  all  the  accessory 
sinuses  at  one  exposure,  it  is  necessary  that  the  rays  pass 
through  the  head  at  a  certain  angle.  If  this  angle  is  not 
observed,  the  petrous  portion  of  the  temporal  bone  obstructs 
the  view  of  the  ethmoids  or  antrum,  or  the  sinuses  are  so 
distorted  that  the  information  given  is  not  correct. 

The  proper  angle  is  one  which  will  cause  the  shadow 
of  the  petrous  portion  to  cut  across  the  lower  one-third 
of  the  orbit  and  upper  one-third  of  the  antrum,  leaving  the 
lower  two-thirds  of  the  antrum  free  and  also  the  upper 
two-thirds  of  the  orbit  clear.  Fig.  155.  The  superior 
portion  of  the  antrum  is  not  so  important,  as  any  condition 
affecting  the  antrum  to  the  extent  of  an  x-ray  diagnosis 
will  involve  the  inferior  portion  as  well.  The  possible 
exception  to  this  is  in  the  case  of  a  fracture  involving  the 
lower  orbital  margin.  In  this  ease  the  petrous  portion 
must  be  thrown  down  into  the  antrum,  or  a  plate  must  be 
made  in  the  vertical  position. 

The  position  described  shows  clearly  all  that  is  re- 
quired of  the  frontals,  ethmoids,  and  antra  on  a  single 
plate,  and  the  sinuses  in  their  proper  relation  and  size. 

To  obtain  this  position  the  principal  ray  must  be  directed 
through  the  head  at  an  angle  of  twenty-three  degrees  from 
a  line  extending  from  the  external  auditory  meatus  to  the 
glabella. 

This  angle  may  be  obtained  by  a  pair  of  dividers  or  a 
permanent  triangle  set  at  an  angle  of  twenty-three  degrees. 
Fig.  156. 


SINUSES  AND  MASTOIDS 


349 


Fig.  155.  Schematic  dravv-ing  illustrating  correct  angle  for  pos- 
teroanterior  accessory  sinus  examination.  The  heavy  lines  indicat- 
ing projection  of  petrous  portion  of  temporal  bone  on  to  the  plate. 
A,  antrum;  E,  ethmoids;  F,  frontal;  P,  petrous;  0,  orbit. 


350 


U.  S.  ARMY  X-RAY  IMANUAL 


The  patient  is  seated  before  an  adjustable  stand,  or  may 
lie  prone  on  a  table.  The  head  rests  face  downward  with 
the  nose  and  forehead  on  an  inclined  plane.  The  inclina- 
tion is  such  as  to  be  comfortable  to  the  patient.     The  head- 


FiG.  156.  Position  for  postero-anterior  examination  of  accessory 
sinuses,  head  resting  on  nose  and  forehead,  central  ray  entering  head 
at  angle  of  23°  from  a  line  from  external  auditory  meatus  to  glabella. 


rest  shown  in  the  illustration  has  an  angle  of  twenty 
degrees.  If  the  patient  is  sitting,  an  adjustable  rest  is 
necessary  to  accommodate  for  the  difference  in  the  length 
of  the  neck  and  shape  of  the  head. 

The  tip  of  the  angle  finder  is  placed  opposite  the  glabella, 
the  short  arm  passing  across  the  external  auditory  meatus, 
the  long  arm  extending  upwards  alongside  the  cone  and 


SINUSES  AND  MASTOIDS 


351 


C3 


O    '-3 


2  ^ 

'-t^  — , 

^  O 

o  o 


■^  'BP 


00  -J 


&€ 

rt 


c5 


352  U.  S.  ARMY  X-RAY  MANUAL 

representing  the  direction  of  the  principal  ray.  The  cone 
is  now  brought  into  alignment  with  the  arm  of  the  finder 
and  brought   down   on  the  head,   making  firm   pressure. 

For  lateral  plates  the  patient  places  the  side  of  the 
head  on  the  platform  holder,  the  head  is  leveled  so  that 
the  sagittal  plane  is  parallel  to  the  plate  and  the  tube  is 
centered  so  that  the  principal  ray  passes  directly  through 
the  frontal  sinus.  This  is  to  obtain  a  true  representation 
of  the  depth  of  the  sinus  and  the  thickness  of  the  anterior 
wall.  The  head  is  clamped  firmly  in  place.  Figs.  157 
and  158. 

For  vertical  examination  there  are  two  positions  which 
will  give  satisfactory  views  of  the  sphenoid  sinus  and  the 
adjoining  structure.  One,  with  the  patient  on  his  back 
and  the  head  extended  over  the  table,  has  been  described 
in  another  chapter  (page  310).  The  other  is  obtained  by 
having  the  patient  sit  in  front  of  an  adjustable  stand. 
The  height  and  angle  of  the  stand  is  adjusted  to  suit  the 
height  of  the  patient  and  to  make  him  comfortable.  The 
chin  is  extended  as  far  as  possible  and  placed  on  the  plate 
which  rests  on  the  stand.  The  stand  is  also  adjusted  at 
such  an  angle  that  the  plate  rests  against  the  clavicle. 
This  places  the  entire  neck  on  the  plate,  from  the  point  of 
the  chin  to  the  clavicle. 

The  head  is  leveled  and  fastened  securely  in  place  with 
clamps.  The  tube  is  adjusted  over  the  vertex  and  centered 
so  that  the  principal  ray  passes  downwards  and  backwards 
through  the  sphenoids.  A  straight  edge  placed  alongside 
the  head  and  passing  through  the  sphenoid  and  center  of 
the  cone  will  show  the  point  on  the  plate  where  the  shadow 
of  the  sphenoid  will  be  thrown.  This  must  be  at  a  point 
well  posterior  to  the  point  of  the  jaw,  but  not  so  far  back 
as  to  throw  the  sphenoid  completely  into  the  shadow  of  the 
larynx.     If  the  sphenoid  shadow  is  thrown  at  the  level 


SINUSES  AND  MASTOIDS  353 

of  the  angle  of  the  jaw  a  good  view  of  the  ethmoid  and 
sphenoid  regions  will  be  secured,  Fig.  159. 


Fig.  159.  Position  for  examination  of  sphenoid  sinus.  Chin  rest- 
ing on  plate  and  extended  well  forward  on  plate.  The  height  of 
table  adjusted  so  that  clavicle  touches  plate,  thus  bringing  entire 
neck  parallel  with  plate,  tube  centered  over  vertex  so  that  central 
ray  will  project  shadow  of  sphenoid  on  plate  at  about  the  angle  of 
the  jaw. 


Interpretation  of  Mastoid  Plates. — In  case  the  pinna 
cannot  be  folded  forward,  due  allowance  must  be  made  for 
the  increased  density  over  the  mastoid  cells  caused  by  the 
shadow  of  the  pinna.  Postauricular  edema  will  cause  a 
haze  over  the  cells,  which  must  not  be  mistaken  for  in- 


354  U.  S.  ARJMY  X-RAY  MANUAL 

flammatory  exudate.  Inspection  of  the  ear  before  radio- 
graphic examination  will  prevent  this  error,  as  allowance 
may  be  made  for  the  increased  density.  Furunculosis  in 
the  canal  is  often  accompanied  by  a  slight  cloudiness  of 
the  cells,  which  must  not  be  mistaken  for  exudate. 

The  mastoid,  being  a  pneumatic  cavity,  will  show  nor- 
mally as  a  honeycombed  structure  with  the  cell  partitions 
clearly  outlined,  so  that  the  degree  of  the  involvement  will 
be  determined  by  the  sharpness  of  these  partitions.  A  sim- 
ple congestion  or  thin  fluid  will  produce  a  general  haze  over 
the  mastoid  structure,  but  the  cell  walls  will  be  clearly 
outlined.  As  the  disease  progresses  and  pus  accumulates, 
the  degree  of  obliteration  of  the  cell  walls  will  determine 
the  extent  of  the  disease  or  the  amount  of  pus.  If  the  con- 
dition has  reached  the  point  of  bone  destruction  the  ne- 
crotic area  will  show  through  the  white  blur  of  the  cell 
involvement  as  a  dark  area.  This  usually  occurs  over  the 
line  of  the  tegmen  tympani,  representing  an  epidural  ab- 
scess, or  over  and  below  the  knee  of  the  lateral  sinus  as  a 
perisinus  abscess. 

This  dark  area  must  be  distinguished  from  a  large  cell 
in  the  midst  of  a  group  of  small  cells.  This  can  usually 
be  done  by  comparison  with  the  opposite  mastoid.  As  a 
rule  the  two  mastoids  are  similar  in  structure.  When  there 
is  a  large  or  small  cell  on  one  side  there  is  usually  a  cor- 
responding cell  on  the  opposite  side.  Then,  too,  a  necrotic 
area  will  have  hazy  edges  while  a  clear  cell  will  be  sharply 
outlined. 

Complete  obliteration  of  the  cell  area  must  be  differen- 
tiated from  sclerosis.  This  is  a  condition  caused  by  re- 
placement of  the  cell  structure  by  dense  bone,  and  the 
shadow  on  the  plate  will  therefore  be  structureless.  The 
area  resembles  the  bone  in  the  rest  of  the  skull,  with  a 
clear-cut  outline  of  the  sinus  showing  through.    This  proc- 


SINUSES  AND  MASTOIDS  355 

ess  can  be  so  extensive  as  to  involve  the  entire  area  in- 
cluding' the  region  of  the  antrum,  thus  showing  no  detail 
at  any  point. 

A  condition  may  arise  in  which  necrosis  has  occurred 
in  the  sclerotic  area,  a  cholesteotoma.  This  will  show 
as  a  dark  spot  within  the  sclerotic  area.  Usually  there  is 
a  lighter  area  in  the  dark  portion  which  represents  a  mass 
of  debris  in  the  necrotic  cavity. 

In  the  event  of  a  fracture  or  injury  extending  through 
the  mastoid  structure  stereoplates  are  necessary.  These 
cases  nearly  always  show  mastoid  change  due  to  the  pres- 
ence of  blood  or  infected  material. 

In  the  event  of  the  involvement  of  both  mastoids  de- 
pendence must  be  placed  on  the  history  and  clinical  evi- 
dence. 

The  size  of  the  cells  plays  an  important  part  in  the 
prognosis.  A  large  pneumatic  mastoid  with  large  antrum 
cells  is  more  likely  to  clear  up  without  operation  than  one 
with  small  cells,  as  the  smaller  cells  are  more  apt  to  clog 
and  stop  drainage. 

]\Iany  cases  which  have  been  operated  and  have  not 
properly  cleared  up  will  reveal  cells  remaining  in  the 
mastoid  process.  These  contain  granulations  which  keep 
up  the  discharge  and  prevent  healing. 

In  the  case  of  children,  it  must  be  remembered  that  the 
mastoid  cells  do  not  develop  until  about  the  age  of  five 
years,  so  that  an  examination  of  a  child  under  this  age  wall 
give  no  useful  information. 

Interpretation  of  Accessory  Sinuses. — Here,  as  in  mas- 
toids, there  are  pneumatic  cavities  which  in  a  normal  con- 
dition allow  the  rays  to  penetrate  readily  and  produce 
dark  areas  on  the  plate.  AVhen  pathological  material  is 
present  the  transparency^  is  reduced,  depending  on  the 
extent  of  the  involvement. 


856  U.  S.  ARMY  X-RAY  MANUAL 

In  the  examination  of  the  frontal  sinuses  a  very  impor- 
tant factor  to  be  considered  is  the  depth  of  the  sinus  and 
the  thickness  of  the  anterior  wall,  as  viewed  on  the  lateral 
plate.  A  sinus  with  a  thick  wall  will  naturally  show  less 
transparency  than  the  same  sinus  with  a  thin  wall.  Hence 
a  sinus  with  a  thin  wall  and  containing  granulations  or  thin 
pus  will  cast  the  same  transparency  as  the  same  sized  sinus 
with  a  thick  wall  but  clear  of  pathological  material.  A 
deep  sinus  will  normally  be  more  transparent  than  a  shal- 
low sinus.  One  must  remember  that  one  or  both  frontal 
sinuses  may  be  absent. 

In  the  case  of  absence  of  frontal  sinuses,  the  lateral 
plate  will  reveal  solid  bony  detail  in  the  frontal  region, 
while  a  single  frontal  will  reveal  bony  detail  through  the 
transparent  area  of  the  sinus  which  is  present.  If  both 
are  present  a  clear  area  will  show  on  the  lateral  plate. 

It  is  impossible  to  distinguish  between  the  shadow  cast 
by  pus  or  by  dense  granulations  in  the  sinuses.  The  diag- 
nosis must  be  made  of  occlusion  of  the  sinuses  by  some 
dense  material.    The  case  history  will  help  to  a  great  extent. 

The  ethmoid  region  must  be  studied  in  both  the  antero- 
posterior and  lateral  positions, — the  diagnosis  resting  on 
the  density  of  the  region  and  the  degree  of  obliteration  of 
the  septa.  Plates  made  in  the  vertical  position  will  indi- 
cate the  affected  side  and  show  whether  the  anterior  or 
posterior  cells  are  involved. 

The  ethmoid  cells  are  sometimes  very  extensive  and  show 
above,  behind  and  below  the  orbit.  In  the  examination  of 
the  maxillary  antrum  the  degree  of  obliteration  of  the 
fine  lines  of  the  walls  determines  the  amount  of  involve- 
ment, although  mucoid  material  will  cause  practically  no 
change  in  the  shadow.  It  may  be  necessary  to  puncture  the 
antrum  through  the  nose  to  clear  up  the  diagnosis  between 
granulations  and  pus. 


ix^tf^ 


TEETH    AND    MAXILLAE 

In  the  study  of  the  teeth  dental  fihns  are  more  satisfac- 
tory than  plates.  Accompanying  illustrations  will  describe 
the  proper  adjustments  of  tube  and  films  or  plates.  Plates 
are  used  when  the  films  cannot  be  put  into  the  mouth,  or 
when  a  large  area  is  required  to  be  shown. 

Placing  the  Film. — Observe  the  following  hints  in 
placing  the  films  in  the  mouth.  All  sharp  corners  of  the 
wax  paper  covering  must  be  folded  over  and  softened,  and 
the  films  themselves  will  become  more  soft  and  pliable  by 
bending  (not  breaking)  them  over  the  end  of  the  finger 
and  thumb  so  that  they  will  take  the  curve  of  the  palate 
or  inner  surface  of  the  mandible  more  readily.  To  pre- 
vent  gagging,  the  patient  is  told  to  breathe_deeply  through 
the  mouth,.wliile_the  film  is  being  placed  in  position.    This       "^ 

causes  the  tongue  to  be  carried  far  back  into  the  pharynx 

where  it  need  not  be  pressed  upon.  In  very  troublesome 
cases  s;Qraying  the  galate  and  pharynx  with^camphor  wa- 
ter, in  addition  to  the  above  precaution,  adds  greatly  to 
the  chance  of  success.  Be  sure  that  the  film  is  far  enough 
into  the  mouth  to  include  all  of  the  root  structure.  The 
position  of  the  film  should  be  carefully  noted  after  the 
patient's  thumb  or  forefinger  is  in  place  to  hold  the  film, 
since  the  wax  paper  moves_ easily  on  a  surface  wet  with 
mucus^  and  the  patient's  hold  may  relax  as  the  operator 
removes  his  hand.  For  the  upper  teeth  no  additional  ^  . 
covering  over  the  wax  paper  is  necessary  or  even  desirable,  ^2!« 
and  there  is  no  better  film  holder  than  the  patient 's  ,left 
1;humb  for  the  upper  teeth  on  the  right  side,  and  the  right 


358 


U.  S.  ARMY  X-RAY  MANUAL 


TEETH  AND  MAXILLA 


359 


y5      «       O      Jii^ 

aj  =4-1    c3   fn 
o3   °   ^   rt 

o  'S  E-t  'o 


>^    (D    CQ 

o 


,  °^s 


360 


U.  S.  AR:\IY  X-RAY  MANUAL 


^  o 


en 
o 
Ph 


cu 


ri3 

bJD 

Itl 

O) 

)-4 
O 

^ 

i> 

So 

'-' 

o 

a 

Oi 

;-( 

^H 

OJ 

q; 

r-^  ^ 

«j 

tn 

*M 

o 

s 

s 

^ 

tn 

•^ 

o 

« 

o 

2 

O) 

a; 

S 

■^ 

^ 

-^j 

o 

m 

^ 

^ 
^ 

C^ 

rr^ 

a 

£ 

^ 

Qi 

^ 

rt 

o 

^ 

•iH 

rt 

i» 

M 

PJ 

O 

O 

o 

be 
as 
S 

4-i 

'o 

^ 

^ 

X 

q; 

o 

'o 

1) 

>;  -i3 

0) 

Xtl 

> 

13 

O 

IS 

'V 

QJ 

rH 

CD 

,£3 

(P 

-4-i 

-M 

O  .G 

-t^ 

-M 

f_f 

O 

C3 

-(-5 

T— i 

=4-1 

s 

o 

+2 

o 

u 

O 

o 

93 

P^ 

o 

^ 

^ 

■^ 

rC 

QJ 

o 

«o 

-4-5 

rP 

GO 

1—1 

qn 

S 

X2 
03 

^ 

O 

J3 

d 

fl 

4^ 

-*-5 

pC 

s 

a; 

5 

g 

e 

Ik 

TEETH  AND  MAXILLA 


361 


362 


U.  S.  AR]MY  X-RAY  MANUAL 


^T^r 

^^^^^     m      ^      1 

^^|j 

m^ 

Fig.  166.  Sarcoma  of  mandible  involving  median  incisors  and  left 
lateral  incisor,  probably  also  beginning  involvement  of  the  other  teeth 
shovm. 


Fig.  167.  Acute  abscess  right  upper  central  and  lateral  incisors. 
Note  that  abscess  is  not  sharply  defined.  Acute  abscesses  sometimes 
do  not  cast  definite  shadows. 


TEETH  AND  MAXILL.E 


363 


364 


U.  S.  ARMY  X-RAY  MANUAL 


TEETH  AND  :\rxVXILL.^  3G5 

thumb  for  those  on  the  left  side.    The  pressure  of  the  thumb 

must  be  firm,  and  the  fingers  should  rest  on  the  opposite 

side  of  the  face  to  prevent  unintentional  motion  of  the 

liand.     Iii^ll  instances  the  operator  must  mold  the  ^1^^^ '^-t^/A,^ 

to  the  contour^ of  the  maxilla3  and  denote  b}^  the  firmness  Z;^^^^  ^ 

of  his  own  pressure  how  the  patient  shajl  hold  it.  ^j^'CCSt^jt 

For  the  lower  jaw  the  films  should  be  wrapped  in  soft 
tissue  paper,  such  as  a  paper  napkin.     This  prevents  slip- 
ping and  is  also  more  comfortable  to  the  patient.     It  is   X^-t^**^ 
absolutely  essential  that  the  patient 's^ tongue  be  completely    "^^-^A-ite* 
relaxed  in  _order  tliat^  the  film  ma3^  be  carried  back  far   "Ln  zV«^ 
enough  to^reach  well^beyond  tlie  third  molar,  anddeep 
eliough  to  reach_j\vell  below  the  apicesof  the  roots.     The 
palmai'  surface  of  the  jjide^^nger  of  the_opposite_hand  is 
preferred  for  holding  the  films  agains^the^lowerjteetlL 

Exposure. — The  patient  should  hold  his  breath  during  '7^  o 
the  actual  exposure  whether  it  is  for  one  second  or  twenty  ^o^^XjS 
seconds.  ^^-CLi^^.^  J^^ 

The  proper  an^giejof  exposure  niust  be  determined  by  the  ' 

contojir_of  the  patient^s^maxill^^  and  the  tooth  shadow  mjj'f^ 
should  be  approximately  the  same  length  as_the  tooth.  f      it^^ 

For  angle  of  exposure  see  Figs.  160-163.  ^ 

Interpretation. — The  x-ray  study  of  the  teeth  and  max- 
illae is  to  be  considered  from  the  viewpoint  of  dentistry 
without  injury,  and  as  Avell  from  the  viewpoint  of  wounds 
incident  to  war  and,  therefore,  of  surgery.  The  former  has 
more  to  do  with  the  general  health  and  efficiency  of  the 
soldier,  while  the  latter  involves  the  repair  and  restoration 
of  these  very  important  parts  after  injury. 

The  reader  is  advised  to  acquaint  himself  with  the 
structural  and  regional  anatomy  of  the  teeth  and  max- 
illae, and  also  to  study  some  recognized  authority  on  the 
pathology  of  these  structures.  The  accompanying  illus- 
trations show  practically  all  of  the  types  of  pathological 


366 


U.  S.  ARMY  X-RAY  MANUAL 


m 

Fig.  170.     Abscesses  involving  unerupted   teeth. 


Fig.  171.  Adjustment  for  exposure  of  anterior  portion  of  upper 
jaw.  Note  large  film  held  between  the  teeth.  The  teeth  shadows  will 
be  very  much  foreshortened. 


TEETH  AND  MAXILLA 


367 


^  o 

CO 

o  — 


o 


-;     CO     i, 

— .  -t-" 

-  £;  o  c 
'^  :^  -^  .2 

a-  o% 

bx  ;f  i  g 


-     op    OD 


^  s 


^  O  O 

•1—3  J-  .^  _>J 

o  O)  o  c3 

+3  S  m  S 


Fh 

O 

•  -H 

^ 

r; 

^H 

+J 

-1-3 

3 

-w 

0 

ri 

O 

fl 

a 

^ 

V) 

o 

«« 

X! 

(11 

bJD 

O 

rt 

«f-, 

,_4 

+i 

-M 

Si 

^ 

-M 

0 

f/l 

^ 

''~^ 

•^ 

< 

c3 

fl 

O^ 

^ 

L^ 

0 

^H 

C 

rto 

0 

^ 

-^j 

UL4 

^1 

0 

& 

368 


U.  S.  ARMY  X-RAY  MANUAL 


lesions  about  which  we  are  herein  concerned,  except  in- 
juries.    Figs.  164  to  170. 

It  is  difficult  to  anticipate  the  sort  of  injuries  one  has 
to  deal  with  in  military  surgery,  and  therefore  difficult 
to  give  definite  instruction  in  the  part  taken  by  the  roent- 


FiG.  174.    Adjustment   for    exposure    of   upper  jaw. 


genologist.  The  following  illustrations  serve  to  show  the 
proper  adjustments  for  the  different  parts  of  the  jaw  bones, 
and  may  be  taken  as  guides  in  most  instances.  The  object 
is  to  have  the  central  rays  pass  in  such  a  direction  that 
the  shadows  of  the  teeth  on  the  near  side  of  the  face  will 
not  fall  in  the  area  that  is  to  be  examined.  Figs.  171  to 
174. 


THORACIC  VISCERA 

Methods  of  Examination. — The  thoracic  viscera  may  be 
studied  either  by  tluoroseopy  or  by  radiography.  Fluoros- 
copy is  useful  for  a  preliminary  orientation,  to  view  the 
movement  of  the  diaphragm,  to  study  the  movement  of 
fluid  levels  in  the  pleura  and  in  the  lung  and  to  observe 
the  mediastinum  in  the  various  oblique  positions.  It  is 
indispensable  in  the  x-ray  study  of  heart  and  aortic  con- 
ditions. It  is  of  uncertain  value  in  the  recognition  of 
infiltration  in  the  lung  as  in  tuberculosis.  For  this  purpose 
a  plate  examination  is  indispensable. 

Stereoscopic  plates  are  of  value  to  indicate  the  depth  of 
a  pulmonary  lesion ;  they  will  diiferentiate  between  pul- 
monary and  pleural  or  extrapulmonary  conditions.  In 
tuberculosis,  especially,  they  resolve  the  shadows  into  their 
components  and,  thus,  give  a  truer  idea  of  the  density  of 
the  infiltration.  Stereoscopy  can,  however,  usually  be  dis- 
pensed with,  as  the  data  it  furnishes  does  not  materially 
differ  in  character  from  that  found  in  a  good  single  plate. 
A  moi'e  potent  reason  for  dispensing  with  it  in  army  work 
is  the  additional  time  and  trouble  involved  and  the  diffi- 
culty of  obtaining  large  plates  in  sufficient  number. 

Time. — The  time  of  a  single  exposure  shoulcj  not  exceed 
two  seconds.  If  the  current  is  not  sufficient  to  obtain  a 
proper  exposure  in  that  time,  the  use  of  an  intensifying 
screen,  w^hich  must  be  as  nearly  perfect  and  free  from 
grain  as  possible,  is  advised.  Exposures  of  less  than  a 
second  are  desirable,  but  at  the  present  time  they  are  not 
easily  accomplished  in  the  routine  work  of  large  hospital 

369 


370 


U.  S.  ARMY  X-RAY  MANUAL 


fj     OT     O 


I 

;-. 

Q 

t-l 

o 

,£2 

13 

•4^ 

-2 

H 

fcJO 

■^ 

PH 

0) 

1"> 

13 

. 

r^ 

-»-> 

n 

-|J 

n 

n3 

-M 

-P 

M 

rt 

^ 

o 

n 

ft 

-M 

OJ 

crt 

QJ 

n3 

CT' 

•4-^ 

oa 

r— H 

!=l 

r" 

a;i 

^ 

O 

CD 

ft 

P=H 

O 

ft 

73 
O 
ft 

■73 

ft 

o 

T— 1 

CO 

n^ 

•  ^ 

O) 

o 

^ 

^ 

M 

1— 1 

o 

0; 

;x^ 

'^ 

O 

CD    t>    O 


THORACIC  VISCERA 


371 


Otj  Qi   en 

02     O 


.2  ^ 

+i   o 


=c-g.2^ 


o 


3  S"S 


o 

fl 

S 

02 

OS 

^ 

13 

IT) 

Si 

OS 

o 

I-:] 

^ 

«H 

o 

0) 

O 

a 

3 
r-i 

a 

m 

© 

o 

71 

X2 

•— ^ 

3 

,^ 

-(-3 

cr 

at 

^ 

^ 

•" 

'A 

^ 

•+J 

'•$. 

o 

j; 

O 

o 

-tJ 

.""" 

4-" 

o 

.1-1 

cs 

^ 

a 

OS 

■^ 

=M 

h 

o 

o 

1- 

<y 

sN 

-M 

m 

3   c;! 

_ ' 

— 

o 

tr  o 

^ 

b£  ^ 

o 

■M 

^    O 

372  U.  S.  ARMY  X-RAY  IMANUAL 

laboratories,  where  they  consequently  increase  the  number 
of  unsuccessful  plates. 

Fosition. — The  position  of  the  patient  should  always  be 
upright,  standing  or  sitting,  and  only  when  there  are  in- 
dications to  the  contrary  should  the  position  be  prone  or 


Fig.  179.  Dorsoventral  (postero-anterior)  position;  chin  raised 
and  neck  extended  so  as  to  avoid  turning  of  head  to  one  side  or  the 
other;  foens  of  tube  approximately  at  level  of  the  4th  thoracic  ver- 
tebra; distance  26  inches. 

recumbent.  In  the  upright  position  it  is  best  to  so  adjust 
the  plate  that  its  upper  margin  will  touch  the  under  sur- 
face of  the  chin,  and  the  upper  part  of  the  chest  should  be 
brought  as  near  to  the  plate  as  possible.  The  arms  should 
be  slightly  raised  and  rotated  inward,  so  as  to  remove 
the  shadows  of  the  scapulae  from  the  lung  field.     Raising 


THORACIC  VISCERA  373 

the  arms  too  liigh  obliterates  the  apices.  If  the  plate  can- 
not be  placed  as  stated,  it  is  advisable  to  extend  the  neck 
and  thus  raise  the  chin,  but  it  is  not  desirable  to  turn  the 
head  to  one  side  or  the  other,  because  it  causes  distortion 
of  the  trachea.  This  position,  which  will  be  called  the  dor- 
so ventral  because  the  tube  is  at  the  back  of  the  patient  and 
the  plate  in  front,  is  the  one  most  commonly  employed 
(Fig.  179).  Other  positions  which  are  necessary  to  bring 
out  certain  structures  in  the  chest  are  the  various  oblique 
positions.  These  are  the  following:  first  oblique — the  tube 
behind  at  the  left,  the  plate  or  screen  in  front  at  the  right 
of  the  patient  (Fig.  175)  ;  second  oblique — the  tube  be- 
hind at  the  right,  the  plate  in  front  at  the  left  of  the  pa- 
tient (Fig.  176)  ;  third  oblique,  a  dorsal  reversal  of  the  first 
(Fig.  177)  ;  fourth  oblique,  a  dorsal  reversal  of  the  second 
(Fig.  178).  The  first  and  third  oblique  bring  out  most 
clearly  the  structures  in  the  posterior  mediastinum  and  are 
most  commonly  used  to  demonstrate  the  esophagus.  The 
second  and  fourth  oblique  are  best  used  to  bring  out  the 
right  side  of  the  heart  and  particularly  the  ascending  aorta. 

The  focus  of  the  tube  should  be  at  the  level  of  the  fourth 
thoracic  vertebra  when  using  the  dorsoventral  position. 
This  shows  the  apices  clearly  and  projects  the  diaphragm 
downwards  so  that  more  lung  tissue  at  the  bases  can  be 
seen. 

The  exposure  should  be  made  at  nearly  full  inspiration. 
Absolutely  full  inspiration  is  not  advisable  because  most 
patients  strain  in  doing  so,  making  it  more  difficult  for  them 
to  hold  their  breath  and  causing  frequent  irregularities  in 
the  appearance  of  the  diaphragm,  especially  the  right,  due 
to  a  spasm  of  the  diaphragmatic  muscle. 

Types  of  X-Ray  Chest  Plates. — No  t^vo  chest  plates, 
even  of  normal  individuals,  are  alike.  ^lany  different 
physical  conditions  are  imposed  by  the  conformation  of 


374  U.  S.  ARMY  X-RAY  IMANUAL 

the  chest  and  all  may  be  within  normal  limits.  Variations 
in  the  technique  of  the  examination  may  give  unusual 
appearances  that  must  not  be  mistaken  for  abnormalities. 
It  is  therefore  necessary,  in  deciding  whether  the  shadows 
on  the  plate  are  due  to  pathological  lung  conditions,  to 
take  into  account  these  normal  variations.  Failure  to  do 
this  accounts  for  most  of  the  disagreement  among  roent- 
genologists in  the  interpretation  of  plates.  It  is  not  pos- 
sible to  describe  adequately  the  characteristics  of  normal 
plates.  They  must  be  seen  and  studied.  The  following 
suggestions  however  are  made. 

The  Normal  Lung. — There  is,  strictly  speaking,  no  such 
thing  as  a  normal  or  typical  lung  plate.  The  size,  shape 
and  graphic  appearance  of  the  lung  fields  vary  with  the 
age  of  the  individual,  the  shape  of  the  thorax  and  with 
previous  pulmonary  disease.  As  far  as  the  x-ray  is  con- 
cerned the  lungs  consist,  on  the  one  hand,  of  the  great 
mass  of  air-containing  vesicles  and,  on  the  other,  of  a 
network  of  bronchi,  blood  vessels  and  lymphatics.  The 
former  do  not  cast  any  shadows  on  the  plate  and  are  re- 
sponsible for  the  aerated  lung  fields.  The  latter  intercept 
the  ray  and  produce  a  shadowy  network  throughout  the 
lung  radiating  from  the  root,  decreasing  in  distinctness  and 
width  toward  the  periphery  where  they  are  barely  visible. 
It  is  the  difference  in  the  prominence  of  tiiese  markings  in 
different  individuals,  or  even  in  the  same  individual  when 
the  technique  is  varied,  which  gives  rise  to  diverse  types  of 
normal  chest  plates. 

All  the  structures  above  enumerated  contribute  to  the 
production  of  these  markings,  although  to  different  ex- 
tents; the  blood  vessels,  especially  toward  the  periphery 
of  the  lung,  are  responsible  for  most  of  them.  The  bronchi 
do  not  cast  distinct  shadows  except  at  the  root  where  they 
are  merged  with  the  hilum  shadows  and  are  sometimes  seen 


THORACIC  VISCERA  375 

in  cross  section  or  in  double  contour.  It  is,  therefore, 
not  possible  to  identify  the  bronchial  tree  as  such  on  the 
plate  or  to  bring  any  abnormal  infiltrations  into  relation 
with  it. 

I\Iueh  of  the  difference  of  opinion  in  regard  to  plates, 
especially  in  tuberculosis,  has  arisen  from  a  wrong  inter- 
pretation of  these  markings.  Their  unusual  prominence  has 
no  significance  in  itself  and  is  not  necessarily  an  evidence 
of  disease  of  the  lung.  Thus,  if  the  contrast  between  the 
aerated  lung  fields  and  the  airless  branchings  is  enhanced, 
the  latter  will  seem  more  prominent.  This  may  be  seen 
in  emphysema,  in  older  people  with  induration  of  all  the 
tissues,  especially  the  blood  vessels,  and  in  the  case  of  de- 
posits of  dust  and  other  foreign  particles  in  the  lymphatics. 
It  will  also  occur  whenever  the  blood  vessels  are  engorged, 
as  in  circulatory  disease,  and  when  the  examination  is  made 
in  the  prone  position.  The  markings  in  the  lower  lobes  are 
usually  wider,  especially  along  the  borders  of  the  heart 
where  an  appearance  of  fairly  broad,  branching  shadows  is 
not  to  be  considered  abnormal. 

Certain  shadows  are  frequently  encountered  in  plates 
which  have  no  relation  to  disease  processes.  It  should  be 
understood  that  if  any  small  area  of  the  plate  is  scru- 
tinized by  itself  it  may  appear  to  contain  shadows.  These 
are  usually  points  of  bifurcation  or  crossing  of  blood  ves- 
sels or  bronchi.  Other  larger  and  denser  shadows,  varying 
in  size  from  two  to  five  millimeters  or  more,  are  prob- 
ably calcareous  lesions  which  are  found  in  a  large  percen- 
tage of  otherwise  normal  lungs.  They  have  no  clinical 
significance.  The  shadows  cast  by  female  breasts  and  pec- 
toral muscles  should  be  noted,  and  inferences  as  to  the  aera- 
tion of  the  lungs  must  not  be  drawn  from  a  wrong  in- 
terpretation of  them.  The  same  is  true  of  the  scapula, 
the  shadow  of  which  overlaps  the  axillary  portion  of  the 


376  U.  S.  ARMY  X-RAY  MANUAL 

chest  if  the  arms  are  not  brought  forward  or  rotated  inward 
during  the  examination.  The  upper  limit  of  the  apex  is 
usually  at  the  level  of  the  lower  border  of  the  second  rib 
posteriorly.  If  for  any  reason  the  apex  is  depressed,  as 
in  eases  of  chronic  tuberculosis,  a  shadow  may  be  seen  just 
below  and  parallel  to  this  rib. 

The  hilum  or  root  of  the  lung  shows  as  an  ill-defined 
mass  of  shadows  which  are  produced  by  the  blood  vessels, 
large  bronchi  and  lymph  nodes  near  the  mediastinum.  It  is 
irregular  in  shape  and  varies  considerably  in  size  and  den- 
sity, depending  upon  the  age  of  the  individual  and  previous 
respiratory  infections.  Here  again  there  is  no  normal  type. 
Usually  the  shadow  does  not  extend  laterally  more  than  an 
inch  beyond  the  spine  and  is  of  moderate  density.  However, 
in  estimating  the  significance  of  the  hilum  shadows  it  should 
be  remembered  that  in  nearly  all  adults  pathological 
changes  have  occurred.  Thus  the  bronchial  nodes,  as  a 
result  of  infection,  tuberculous  or  otherwise,  are  usually 
enlarged,  indurated  and  calcareous,  and  the  tissues  about 
them  may  be  thickened. 

They  are  only  an  evidence  of  the  usual  adenopathy 
found  in  adults,  and  should  be  disregarded  unless  they 
are  very  marked.  The  hilum  shadows  are  more  prominent 
in  the  aged  and  in  cases  of  emphysema.  If  the  heart  is 
median  in  position  or  hypoplastic,  more  of  the  hilum  will 
be  exposed  and  will,  therefore,  appear  larger. 

The  trachea  takes  an  almost  median  course  through  the 
upper  mediastinum  and  bifurcates  at  the  level  of  the  fourth 
dorsal  vertebra.  It  is  usually  well  seen  on  the  plate  and  a 
deviation  in  its  course  or  a  constriction  are  readily  noted. 
The  bifurcation  and  the  outlines  of  the  larger  branches  of 
the  bronchi  are  often  visible  in  a  well-exposed  plate  through 
the  denser  structures  of  the  mediastinum.  The  rest  of  the 
bronchial   tree   is   invisible   and   indistinguishable   in   the 


TITORACIC  VISCERA  377 

lung  fields.  For  this  reason  a  localization  of  the  bronchi 
is  not  generally  possible  and  such  a  localization  is  probably 
of  little  importance. 

Localization  of  the  lobes  of  the  lungs  has  a  greater  value 
and  is  to  a  certain  extent  feasible.  A  knowledge  of  the 
topographical  anatomy  of  the  fissures  is  essential.  On  the 
left  side  the  fissure  between  the  upper  and  the  lower  lobes 
begins  behind  at  the  level  of  the  third  dorsal  vertebra,  ex- 
tends obliquely  down  to  the  axilla  and  then  almost  trans- 
verseh"  across  the  chest  to  the  sternal  end  of  the  sixth  costal 
cartilage.  On  the  right  side  the  upper  interlobar  fissure 
runs  across  the  chest  to  the  sternal  end  of  the  fourth 
cartilage.  By  means  of  these  landmarks  it  is  to  a  cer- 
tain extent  possible  to  refer  shadows  to  individual  lobes. 
This  must,  however,  be  done  with  caution  because,  in  the 
middle  area  of  the  lung,  the  lobes  overlap.  To  localize 
shadows  in  this  region,  stereoscopic  examination  and  the 
oblique  positions  are  of  value.  In  a  fair  proportion  of 
cases  the  right  interlobar  fissure  is  sharply  outlined  on  the 
plate  due  to  pleural  thickening,  thus  serving  as  a  guide  in 
this  region. 
Pulmonary  Tuberculosis — 

Eelation  of  the  X-Ray  to  the  Clinical  Examination. — 
There  are  definite  limitations  to  the  x-ray  diagnosis  of 
tuberculosis,  and  it  is  no  reflection  on  its  value  to  empha- 
size them.  In  order  to  cast  a  shadow  of  sufficient  size  and 
distinctness  to  be  recognized  on  the  plate,  a  mass  of  tuber- 
culous tissue  in  the  lung  must  be  some  millimeters  in 
diameter.  It  therefore  follows  that  a  plate  may  give  no 
evidence  of  an  early  tuberculous  process.  On  the  other 
hand,  it  is  only  fair  to  state  that  at  this  stage  there  are  in 
most  cases  no  physical  signs  or  only  equivocal  ones.  In 
the  vast  majority  of  cases  in  which  the  physical  signs  of 
so-called  incipient  tuberculosis  are  found,  a  careful  plate 


378  U.  S.  AR]\IY  X-RAY  MANUAL 

examination  will  reveal  the  shadows  of  infiltrations.  More- 
over, in  a  fair  percentage  of  cases  the  extent  of  these  in- 
filtrations is  such  as  to  indicate  that  the  process  is  no  longer 
incipient.  In  the  more  advanced  forms  of  tuberculosis  the 
plate  almost  invariably  shows  more  extensive  involvement 
than  is  indicated  by  the  physical  examination. 

The  earliest  infiltrations  of  tuberculosis  are  but  rarely 
visible  on  the  fluoroscopic  screen,  even  at  a  time  when  the 
plate  will  definitely  show  them.  In  the  absence  of  such  in- 
filtrations, a  fluoroscopic  diagnosis  of  early  apical  tuber- 
culosis is  often  made  because  of  deficient  aeration  in  one 
or  the  other  apex.  Such  a  change  in  aeration  may  de- 
pend on  several  causes  other  than  tuberculosis  and,  there- 
fore, is  not  of  gfeat  diagnostic  value.  The  expedient  of 
having  the  patient  cough  and  noting  whether  the  apex 
clears  up  is  an  uncertain  one  and  will  not  definitely  dis- 
tinguish an  atelectasis  from  an  infiltration.  The  fiuoroscope 
should  therefore  be  used  in  the  diagnosis  of  early  tuber- 
culosis only  through  necessity,  not  by  choice.  Even  in  the 
advanced  forms  of  tuberculosis  this  method  will  not  reveal 
the  extent  of  the  process  as  faithfully  as  the  plate,  but  is 
of  great  value  in  the  study  of  the  movement  of  the  dia- 
phragm, since  in  a  considerable  percentage  of  the  cases  of 
early  tuberculosis  the  diaphragm  is  partly  or  completely  im- 
mobile on  the  affected  side.  This  appears  to  occur  irrespec- 
tive of  the  presence  of  diaphragmatic  adhesions. 

X-Ray  Evidence  of  Early  Tuberculosis. — The  early  le- 
sions of  tuberculosis  generally  appear  in  the  upper  lobes, 
and  are  uiually  found  just  below  the  clavicle  and  not  neces- 
sarily.~abfive_jt.  Frequently  they  occur  near  the  apex  of 
the  axilla,  and  appear  usually  as  a  group  ^f  faint  homo- 
geneous shadows,  indistinct  in  outline,  varying  in  diameter 
from  several  millimeters  to  a  centimeter.  The  pathological 
basis  of  these  shadows  is  probably  an  agglomeration  of  tu- 


THORACIC  VISCERA  379 

bercles  surrounded  by  a  pneumonic  exudate.  As  these 
lesions  progress  the  shadows  increase  in  number  so  that- 
"they  coalesce,  producing  a  larger  liomogeneous  shadow.  A 
caseation  of  the  lesions,  which  usually  supervenes,  is  rep- 
resented on  the  plate  by  an  increase  in  the  density  of  the 
shadows  which  become  more  distinct  and  irregular  in  out- 
line. In  most  cases,  sooner  or  later,  there  is  noted  a  de- 
velopment of  fibrous  tissue  which  shows  as  fine  strands  in 
the  infiltrated  area. 

AVhile  the  radiographic  image  varies  according  to  the 
state  and  duration  of  the  lesion,  yet  the  foregoing  descrip- 
tion represents  a  fairly  frequent  form  of  early  tubercu- 
losis. 

In  order  to  diagnose  incipient  tuberculosis  there  must 
exist  one  or  a  group  of  infiltrations  as  above  described;  to 
l;)ase  it  on  the  presence  of^trands  radiating  from  the  root 
of  the  lungs  will  lead  to  frequent  error.  The  importance 
of  observing  a  careful  technique  is  nowhere  so  great  as  in 
the  diagnosis  of  an  early  lesion,  because  here  it  is  vital  to 
eliminate  the  errors  and  confusion  resulting  from  an  undue 
prominence  of  the  lung  markings. 

Advanced  Tuhercidosis. — In  the  progress  of  the  disease, 
as  shown  by  the  plate,  a  great  diversity  of  appearances  is 
produced,  in  the  first  place,  by  the  slow  or  rapid  extension 
of  the  process  and,  in  the  second  place,  by  a  change  in  the 
appearance  of  the  shadows  due  to  the  chronicity  of  the 
lesions.  In  general,  the  density  of  the  infiltration  dimin- 
ishes from  above  downward,  and  in  even  the  most  advanced 
cases  the  bases  show  considerable  aeration.  Although  the 
nodular  character  of  the  tuberculous  process  may  be  ob- 
scured by  an  exudate  or  by  fibrosis,  evidences  of  it  can 
usually  be  found  in  the  peripheral  or  more  recent  lesions. 
The  shadows  vary  from  numerous  discrete  nodular  deposits, 
submiliary  in  size,  characteristic  of  tuberculous  broncho- 


380  U.  S.  ARMY  X-RAY  MANUAL 

pneumonia,  to  complete  consolidation.  On  the  other  hand, 
the  appearance  of  consolidation  may  be  simulated  by  the 
confluence  of  shadows  in  cases  of  tuberculous  broncho- 
pneumonia. 

In  all  but  the  most  rapidly  developing  forms  of  tuber- 
culosis, there  will  be  found  somewhere  in  the  lung  evidence 
of  fibrosis.  This  is  most  marked  in  the  oldest  lesions  in  the 
upper  lobes.  It  consists  of  coarse  linear  or  broader  shadows 
which  commonly  extend  from  the  upper  mediastinum  into 
the  affected  lung.  The  effects  of  these  strands  of  con- 
nective tissue  are  seen  frequently  in  a  displacement  of  the 
thoracic  viscera  and  a  deformity  of  the  thorax.  The 
trachea  is  commonly  pulled  over  toward  the  side  of  the 
oldest  lesion  and  may  take  a  tortuous  course  through  the 
upper  chest.  The  displacement  of  the  trachea  to  either  side 
may  thus  occasionally  give  rise  to  the  physical  signs  of  a 
cavity  near  the  border  of  the  sternum.  The  heart  may  also 
be  displaced  and  there  may  be  a  scoliosis  of  the  spine  and 
retraction  of  the  ribs  and  of  the  chest  wall.  The  diaphragm 
may  be  drawn  up  and  deformed  by  adhesions.  The  chronic 
forms  of  tuberculosis  are  definitely  shown  in  cases  where 
emphysema  and  asthma  are  also  present.  Emphysema,  in 
these  cases,  usually  masks  the  physical  signs  but  reveals  the 
infiltration  on  the  plate  more  clearly  by  contrast. 

Progress  of  the  Lesion. — The  appearance  of  the  lesion  in 
a  nonprogressive  case  may  be  unchanged  over  a  long  period 
of  time.  On  the  other  hand,  a  rapid  extension  of  the  proc- 
ess may  sometimes  be  noted.  For  example,  after  a  hemor- 
rhage or  the  overflow  of  secretions  from  a  cavity  in  an 
upper  lobe,  a  dense  shadow  due  to  a  caseous  lobar  or 
bronchopneumonia  in  the  lower  lobe  may  be  seen  to  de- 
velop in  a  short  time.  Tuberculous  infiltrations  once  noted 
in  the  plate  are  usually  permanent.  Even  with  an  im- 
provement in  the  symptoms  the  shadows  persist,  though 


THORACIC  VISCERA  381 

they  may  be  changed  somewhat  in  appearance  by  fibrosis 
or  calcification.  The  only  exception  to  this  statement  ap- 
pears to  be  in  the  case  of  the  pneumonic  process  which  sur- 
rounds the  early  lesions.  For  example,  in  the  acute  stage 
of  incipient  tuberculosis  there  is  occasionally  seen  a  rather 
extensive  shadow  in  an  upper  lobe,  much  of  which  dis- 
appears after  the  period  of  acute  illness  is  gone.  A  small 
permanent  remnant  of  the  infiltration  will  indicate  its 
tuberculous  nature. 

In  cases  of  suspected  tuberculosis  we  may  find  an  in- 
filtration of  a  lower  lobe.  In  deciding  the  nature  of  such 
a  shadow  the  coincidence  of  a  process  at  an  apex  is  of  the 
greatest  importance.  It  may  be  taken  as  a  working  rule 
which  applies  to  the  vast  majority  of  cases,  that  in  adults 
an  isolated  infiltration  in  a  lower  lobe  is  probably  not  tuber- 
culous. It  should  provisionally  be  attributed  to  some  other 
condition,  such  as  lung  abscess  or  bronchiectasis  or  an  in- 
durative pneumonia. 

Tuberculous  Cavities. — Cavities  are  not  necessarily  an 
evidence  of  far-advanced  tuberculosis,  as  they  may  occur 
in  cases  with  only  a  small  involvement  of  an  upper  lobe. 
Occasionally  they  may  be  found  well  encapsulated,  with  no 
evidence  of  infiltration  elsewhere  in  the  lung.  They  are 
usually  easy  of  recognition  on  the  plate  or  fluoroscope,  and 
are  often  discovered  when  physical  signs  are  lacking.  They 
appear  as  well-defined,  ringlike  structures,  w^hich  are  im- 
bedded within  the  infiltrated  lung  with  a  connective  tissue 
capsule.  The  commonest  sizes  encountered  are  from  one  to 
three  inches  in  diameter.  Cavities  less  than  one  inch  in 
diameter  are  usually  difficult  of  recognition,  either  because 
they  are  deeply  seated  within  the  infiltrated  lung  or  because 
they  contain  little  air  or  have  no  definite  capsule.  Again, 
larger  cavities  may  not  be  recognized  if  they  are  full  of 
secretion  and,  therefore,  cast  a  dense  shadow  indistinguish- 


382  U.  S.  ARMY  X-RAY  MANUAL 

able  from  the  infiltrated  lung  in  which  they  lie.  Occasion- 
ally the  outlines  of  several  cavities  may  overlap.  Tuber- 
culous cavities  do  not  usually  have  the  punched-out  appear- 
ance commonly  found  in  abscess  of  the  lung  nor  do  they 
usually  show  a  fluid  level.  If  at  all,  fluid  is  seen  only  in 
the  larger  ones.  Cavities  are  most  commonly  found  in  the 
upper  lobes  and  only  rarely  at  the  bases.  The  shadows  in 
an  infiltrated  lung  frequently  give  rise  to  deceptive  ap- 
pearances by  enclosing  circular  spaces  which  may  simulate 
cavities.  Confusion  may  also  arise  at  the  hilum  of  the 
lung  from  the  cross  section  of  the  larger  bronchi  and  the 
spaces  enclosed  by  branching  blood  vessels. 

Tuberculosis  of  the  Bronchial  Nodes  and  Hilum. — In 
most  adults,  as  a  result  of  respiratory  infection,  tubercu- 
lous or  otherwise,  or  of  dust  inhalation,  the  bronchial  lymph 
nodes  are  enlarged  and  indurated  and  may  contain  lime  de- 
posits. The  lung  tissue  between  the  nodes  is  also  frequently 
thickened.  These  changes  are  readily  noted  on  the  plate. 
At  times  we  can  distinguish  an  enlargement  of  the  various 
groups  of  nodes  such  as  the  paratracheal,  the  bifurcated, 
the  bronchial  or  the  bronchopulmonary.  These  changes  at 
the  roots  of  the  lungs  have  little  value  in  diagnosis  as  they 
are  found  in  the  majority  of  adults  who  are  apparently 
well.  The  plate  cannot  determine  whether  these  enlarged 
nodes  are  actively  diseased  and  therefore  responsible  for 
the  patient's  symptoms  at  the  time. 

The  term  hilum  tuberculosis  should  be  reserved  for  the 
cases  in  which  the  disease  begins  at  the  root  of  the  lung  and 
extends  outward  into  it.  The  diagnosis  should  only  be  made 
if  the  root  structures  are  extensively  infiltrated.  Cases  of 
anthracosis,  emphysema  or  chronic  bronchitis  may  result  in 
the  same  modification  of  the  hilum  shadows  as  this  form  of 
tuberculosis. 

Miliary  Tuberculosis. — Miliary  tubercles,  when  solitary, 


THORACIC  VISCERA  383 

are  too  small  to  give  visible  shadows.  When  they  are  closely 
studded,  however,  as  in  general  miliary  tuberculosis, 
groups  of  tubercles  will  cast  shadows  which  can  be  recog- 
nized as  infiltrations.  They  are  about  two  to  three  milli- 
meters in  diameter  and,  in  their  early  stages,  are  so  indis- 
tinct as  to  give  the  lung  a  uniformly  mottled  appearance. 
A  few  days  or  a  week  after  their  first  discovery  they  are 
more  distinct  and  the  appearance  is  unmistakable.  The  den- 
sity of  the  shadows  diminishes  from  the  apex  to  the  base. 
The  plate  reveals  their  presence  long  before  they  produce 
definite  physical  signs  and,  for  this  reason,  is  of  decisive 
value  in  some  cases  of  obscure  disease.  Tuberculous  bron- 
chopneumonia may  assume  a  miliary  form  which  may 
closely  simulate  general  miliary  tuberculosis.  In  the  former, 
however,  the  infiltrations  are  more  sharply  outlined,  are  apt 
to  be  arranged  along  the  course  of  the  lung  markings,  and 
there  is  evidence  of  an  older  process  in  the  upper  lobe. 

Activity. — Activity  cannot  be  determined  from  an  x-ray 
examination.  We  do  know,  however,  that  a  great  amount 
of  fibroid  tissue  in  a  given  lesion  indicates  chronicit3\ 
What  we  cannot  determine  is  a  lighting  up  of  an  active 
process  in  an  old  lesion.  We  must  remember  that  the  plate 
only  shows  anatomical  changes  and,  while  certain  deduc- 
tions can  be  made,  they  do  not  coincide  necessarily  with 
the  clinical  signs.  After  all,  tuberculosis  is  a  clinical  dis- 
ease, and  we  form  our  opinions  of  activity  upon  the  gen- 
eral condition  of  the  patient,  namely,  fever,  weakness,  loss 
of  weight,  cough,  tubercle  bacilli,  rales,  etc.  None  of  these 
important  manifestations  can  be  determined  by  the  x-ray 
examination. 

The  x-ray  examination  shows  the  extent  of  the  lesion 
more  accurately  than  the  physical,  but  to  obtain  the  best  re- 
sults a  combination  of  the  clinical  and  x-ray  examinations 
is  the  ideal  method. 


384  U.  S.  ARMY  X-EAY  MANUAL 

Pneumonia. — In  lobar  pneumonia  there  is  seen  a  uni- 
form shadow  coextensive  with  one  or  more  lobes  of  the 
lung.  In  the  early  stages  this  shadow  may  be  very  faint. 
In  the  case  of  the  upper  lobe,  especially  on  the  right  side, 
this  shadow  is  usually  somewhat  denser  and  is  sharply  lim- 
ited by  the  interlobar  fissure.  The  shadow  cast  by  a  lower 
lobe  pneumonia  often  appears  smaller  than  would  be  ex- 
pected, so  that  its  upper  border  may  extend  only  a  short 
distance  above  the  diaphragm.  The  whole  lobe  is  not  neces- 
sarily involved,  or  it  may  not  be  uniformly  consolidated. 
The  diaphragm  is  clearly  visible  below  the  infiltration,  al- 
though its  movement  may  be  retarded.  The  infiltration 
may  persist  far  into  the  period  of  convalescence,  so  that 
the  examination  may  disclose  shadows  when  physical  signs 
are  no  longer  present.  The  recession  of  a  pneumonic  proc- 
ess apparently  may  proceed  in  an  irregular  way.  As  a  re- 
sult the  examination  may  show  clearer  areas  within  the 
infiltration,  which  may  be  confused  with  abscess  cavities. 
Lobular  and  bronchopneumonia  in  the  great  majority  of 
cases  do  not  cast  appreciable  shadows.  A  tuberculous  pneu- 
monia, especially  in  the  upper  lobe,  may  cast  a  shadow  in- 
distinguishable from  that  of  an  ordinary  pneumonia.  Here 
the  diagnosis  must  wait  on  the  clinical  history  and  the 
sequel.  Postpneumonic  empyema  can  be  recognized  at  an 
early  stage.  The  diaphragm  in  its  outer  portion  becomes 
obscured,  and  the  costophrenic  sinus  is  occupied  by  a 
shadow  which  is  denser  than  that  of  the  neighboring  lung. 

In  cases  of  persistent  pneumonia  with  induration  of  the 
lung,  the  condition  can  be  accurately  studied.  As  a  re- 
sult of  the  formation  of  fibrous  tissue,  the  shadows  become 
much  denser  and,  if  large  bronchiectatic  cavities  result, 
these  can  be  observed  on  the  plate. 

Streptococcic  bronchopneumonia  frequently  produces 
shadows  on  the  x-ray  plate  difficult  to  differentiate  from 


THORACIC  VISCERA  385 

those  of  tuberculosis.  The  entire  lung  field  may  be  dotted 
with  small  distinct  shadows  similar  to  those  seen  in  miliary 
tuberculosis.  Again,  there  may  be  larger  and  irregular 
shadows  in  the  parenchyma,  some  faint  and  others  rather 
distinct,  like  those  produced  by  conglomerate  tubercles  or 
multiple  tuberculous  foci.  The  streptococcic  bronchopneu- 
monias are  often  associated  with  localized  empyemata  and 
•  gradually  clear  up  under  several  months'  observation, 
which  is  not  true  of  tuberculosis. 
Diseases  of  the  Pleura — 

Fleurisy. — The  diagnosis  of  dry  pleurisy  is  usually  diffi- 
cult. A  thin  plastic  exudate  may  not  sufficiently  intercept 
the  rays  to  produce  a  perceptible  shadow.  Only  at  times 
does  one  see  at  the  bases  coarse  linear  shadows  produced  by 
denser  exudates.  On  the  screen  there  is  noted  a  restriction 
or  absence  of  diaphragmatic  movement  on  the  affected  side. 

In  chronic  tuberculosis  and  in  cases  of  pleuropneumonia 
the  thick  pleura  may  produce  a  very  dense  homogeneous 
shadow  of  wide  extent  entirely  obliterating  the  lung 
markings.  The  diaphragm  is  usually  invisible  and  it  may 
be  difficult  to  distinguish  this  condition  from  that  of  a 
large  pleural  effusion.  A  retraction  of  the  chest  wall  and 
displacement  of  the  heart  and  mediastinum  towards  the 
affected  side  will  render  the  diagnosis  of  pleural  thickening 
more  probable. 

Pleural  Effusions. — The  shadows  cast  by  pleural  effu- 
sions are  readily  recognized  by  their  usual  location  in  the 
axillary  portion  of  the  chest.  When  small,  they  produce  a 
dense  uniform  shadow  at  the  base  of  the  axilla  which  fills 
up  the  costophrenic  sinus  and  obscures  the  outline  of  the 
diaphragm  in  its  outermost  portion.  At  this  stage  the 
level  of  the  fluid  is  concave  upwards.  As  the  fluid  increases 
this  shadow  rises  until  it  may  reach  the  apex  occupying  the 
entire  chest.     Even  in  such  large  effusions,  however,  the 


386  U.  S.  ARMY  X-RAY  ]\1ANUAL 

compressed  and  airless  lung  may  be  seen  indistinctly  near 
the  upper  mediastinum.  In  larger  effusions  the  upper 
level  may  become  straight  or  convex  upwards  and  is  indis- 
tinct; the  diaphragm  is  invisible. 

On  fluoroscopic  examination  the  level  of  the  fluid  may 
show  a  slight  shifting.  This,  however,  is  not  as  marked 
as  is  commonly  supposed  and  takes  place  slowly,  probably 
due  to  conditions  which  interfere  with  the  free  movement 
of  the  fluid. 

The  sequence  above  described  is  that  commonly  seen  in 
the  chest  of  adults.  In  young  individuals,  an  effusion  may 
have  its  beginning  as  a  thin  layer  of  fluid  which  extends 
along  the  periphery  of  the  lung  from  apex  to  base.  This 
is  represented  on  the  plate  by  a  narrow  shadow  of  uniform 
width,  in  the  axillary  portion  of  the  chest  reaching  from 
the  summit  to  the  base  of  the  lung.  As  the  fluid  accumu- 
lates the  lung  is  no  longer  able  to  support  it,  and  it  gravi- 
tates to  the  bottom  of  the  chest.  It  then  assumes  the  ap- 
pearance above  described  for  adults. 

The  secondary  changes  in  the  chest  resulting  from  pleural 
effusions  are  variable.  While  displacement  of  the  heart  and 
mediastinum  are  often  noted,  there  may  be  none  even 
with  large  effusions.  On  the  other  hand,  a  beginning 
pleurisy  may  cause  displacement  of  the  heart.  Nor  is  the 
freedom  or  encapsulation  of  the  fluid  the  determining  ele- 
ment, as  walled-off  effusions  may  displace  the  heart  to  the 
opposite  side. 

Pleural  effusions  are  frequently  encapsulated  by  ad- 
hesions and  the  resulting  shadows  may  be  atypical.  It  is 
difficult  to  describe  their  many  varieties.  An  encapsulated 
effusion  most  often  occupies  the  axillary  portion  of  the 
chest,  and  in  one  of  its  common  forms  is  sharply  bounded 
mesially  and  set  off  from  the  compressed  lung.  Its  out- 
line may  suggest  a  sacculation  into  two  or  more  compart- 


THORACIC  VISCERA  387 

ments.  As  most  of  them  extend  to  the  base,  the  diaphragm 
may  be  partly  or  wholly  obscured.  Occasionally  an  effu- 
sion may  be  localized  over  an  upper  lobe  and  simulate  a 
pneumonic  consolidation.  Here  a  definite  diagnosis  may  not 
be  possible. 

Interlobar  effusions  are  not  very  common.  Cases  thus 
diagnosed  clinically  are  more  often  examples  of  encapsu- 
lated effusions  in  the  general  pleural  cavity.  The  com- 
monest and  most  easity  recognized  occupies  the  upper  right 
interlobar  fissure.  It  may  be  combined  with  a  general  or 
encapsulated  eff"usion.  It  appears  as  a  homogeneous  shadow, 
usually  triangular  in  shape,  traversing  the  chest  hori- 
zontally at  the  level  of  the  fissure.  In  width  it  is  less  than 
that  of  an  intercostal  space,  the  shadow  being  greatest  and 
most  distinct  near  the  axilla.  The  oblique  positions  are 
helpful  in  this  examination. 

An  uncommon  form  of  encapsulated  effusion  is  the  so- 
called  mediastinal  pleurisy,  in  which  the  fluid  occupies  the 
mesial  portion  of  the  chest,  lying  close  to  the  mediastinum. 
The  shadow  here  is  confluent  with  that  of  the  heart. 

X-ray  examination  furnishes  little  distinction  between  a 
serous,  purulent  or  hemorrhagic  exudate. 

Pneumothorax  and  Hydro-  or  Pyopneumothorax. — A 
moderate  degree  of  pneumothorax  reveals  the  edge  of  the 
partly  retracted  lung  a  variable  distance  from  the  chest- 
wall,  the  space  previously  occupied  by  it  showing  an  absence 
of  lung  markings.  With  an  increase  in  the  amount  of  air 
in  the  pleural  cavity  the  lung  is  crowded  upward  and  in- 
ward to  the  spine,  and,  with  marked  positive  pressure,  may 
even  be  displaced  together  wdth  the  mediastinum  into  the 
opposite  chest.  In  extreme  cases  the  edge  of  the  medias- 
tinum may  present  in  the  opposite  chest  a  curved  linear 
shadow  with  its  convexity  outw^ard.  Frequently  such  a 
complete  pneumothorax  is  prevented  by  adhesions  which 


388  U.  S.  ARMY  X-RAY  MANUAL 

may  immobilize  any  portion  of  the  lung.  The  location  and 
character  of  these  adhesions  can  be  readily  determined  on 
the  plate.  The  pneumothorax,  if  of  large  extent,  may  de- 
press the  diaphragm  and  interfere  with  its  movements. 
The  soft  tissues  of  the  neck  and  thorax  should  always  be 
examined  to  determine  the  presence  of  subcutaneous  em- 
physema. 

Whenever  air  and  fluid  are  simultaneously  present  in 
the  chest  the  latter  acquires  a  horizontal  level.  This  fact 
is  of  importance  in  diagnosis,  as  the  presence  of  such  a  level 
in  the  chest,  if  not  due  to  a  cavity  in  the  lung,  always  in- 
dicates air  in  the  pleural  cavity.  It  is,  thus,  frequently 
noted  in  cases  of  pleural  effusion  in  which  incomplete 
aspiration  has  been  performed  and  a  small  amount  of  air 
accidentally  introduced.  It  portrays  faithfully  any  num- 
ber of  sacculations  in  a  case  of  hydro  or  pyopneumothorax 
with  adhesions  in  which  each  pocket  of  pus  has  its  fluid 
level  with  a  bubble  of  air  above  it,  the  former  shifting  im- 
mediately on  change  of  position  unlike  effusions  without 
air. 

The  examination  is  indispensable  to  the  proper  per- 
formance of  artificial  pneumothorax  in  pulmonary  tuber- 
culosis. It  determines  whether  air  is  actually  introduced, 
whether  it  has  passed  into  the  pleural  cavity  or  into  the  sub- 
cutaneous tissues  or  under  the  diaphragm.  It  may  dis- 
close the  cause  of  failure  of  the  operation,  such  as  pleural 
adhesions.  These  it  localizes,  determines  their  size  and  ap- 
parent strength  and  whether  they  are  apt  to  be  reduced. 
Finally  the  examination  will  indicate  when  the  pneumotho- 
rax is  complete  and  the  degree  of  mediastinal  displacement. 

The  examination  is  also  of  value  in  the  study  of  pneu- 
mothorax following  operation  for  empyema.  Here  one 
can  accurately  note  the  size  and  shape  of  the  sinus,  the 
presence  of  retained  pus  and  the  efficiency  of  the  drainage. 


THORACIC  VISCERA  389 

The  Diaphragm. — The  shape  and  position  of  the  normal 
diaphragm  are  subjeet  to  considerable  variation,  depend- 
ing on  the  shape  of  the  thorax.  Thus,  in  broad-chested  in- 
dividuals it  is  higher  in  position  and  its  convexity  is 
greater.  In  the  asthenic  type  of  chest  it  is  depressed  and 
flatter  in  contour.  The  costophrenic  sinus  should  be  sharp 
and  clear  and  should  increase  in  width  and  depth  on  deep 
breathing. 

The  contour  of  the  diaphragm  is  usually  smooth.  Os- 
casionally,  on  deep  breathing,  owing  to  irregular  contrac- 
tion of  its  muscular  bundles,  its  outline  may  be  broken  up 
into  several  smaller  convex  curves.  These  must  not  be 
confused  with  pleural  adhesions  or  with  subdiaphragmatic 
conditions.  Pleural  adhesions  give  rise  to  fine-pointed 
projections  on  its  surface.  If  these  adhesions  are  broad 
they  may  produce  only  an  indistinctness  in  its  outline.  A 
common  evidence  of  old  pleurisy  is  an  obliteration  of  the 
costophrenic  sinus  by  adhesions. 

The  position  of  the  diaphragm  is  often  an  indication  of 
disease  of  the  structures  in  its  vicinity.  In  cases  of  dry 
pleurisy  and  lobar  pneumonia  it  is  usually  slightly  ele- 
vated. The  dome  of  the  diaphragm  may  reach  an  extreme 
height  in  the  chest  in  cases  of  ascites,  gaseous  distension  or 
abdominal  tumor.  A  subphrenic  abscess  may  cause  a  uni- 
lateral elevation  of  the  diaphragm.  If  this  is  of  slight  de- 
gree, it  is  difficult  to  distinguish  from  a  pleurisy.  The 
diagnosis  of  a  subphrenic  abscess  is  only  warranted  if  the 
upward  displacement  of  the  diaphragm  is  considerable.  A 
subdiaphragmatic  gas  abscess,  especially  on  the  right  side, 
produces  a  characteristic  picture  of  a  fluid  level  under  the 
right  diaphragm  surmounted  by  a  crescentic  bubble  of 
air.     The  fluid  shifts  on  change  of  position. 

Eventration  of  the  diaphragm  and  diaphragmatic  hernia 
produce  a  similar  appearance.     The  thinned-out  and  atro- 


390  u.  s.  ar:\iy  X-ray  manual 

phic  diaphragm  is  pushed  high  up  into  the  chest  by  the 
distended  viscera  below  it,  at  times  extending  to  the  level 
of  the  second  rib.  Eventration  of  the  diaphragm  usually 
occurring  on  the  left  side,  there  is  commonly  a  marked  dis- 
placement of  the  heart  to  the  right  so  that  a  condition  of 
dextrocardia  is  closely  simulated.  Occasionally,  tumors 
of  the  liver  may  produce  a  local  prominence  on  the  dome 
of  the  diaphragm.  This  must  not  be  confused  with  mus- 
cular contractions. 

The  movement  of  the  diaphragm  must  be  studied  with  the 
screen.  It  varies  in  extent  according  to  the  predominance 
of  costal  or  diaphragmatic  breathing.  In  many  cases  of 
incipient  tuberculosis  the  diaphragm  on  the  affected  side 
is  restricted  or  even  inhibited  in  its  contractions.  This 
may  occur  independently  of  any  adhesions.  It  is  very 
common  in  advanced,  especially  fibroid  tuberculosis.  In 
lobar  pneumonia  a  paretic  diaphragm  may  persist  far  into 
convalescence.  Adhesions  may  affect  the  movement  of  the 
whole  or  part  of  the  diaphragm.  Thus  pericardial  ad- 
hesions may  cause  a  lagging  of  only  its  mesial  portion. 
The  so-called  paradoxical  movement  of  the  diaphragm  oc- 
curs in  cases  of  large  pneumothorax  and  in  eventration,  the 
movement  being  in  the  opposite  direction  from  the  physio- 
logical. Complete  paralysis  may  be  observed  in  bulbar 
palsy  or  in  poliomyelitis  and  after  operative  section  of  the 
phrenic  nerve. 

Lung  Abscess  and  Bronchiectasis. — From  an  x-ray 
standpoint  it  is  in  most  cases  not  possible  to  distinguish  be- 
tween abscesses  which  arise  from  dilated  bronchi  and  those 
which  have  developed  from  an  immediate  breaking  down  of 
lung  tissue.  Such  a  diagnosis  must  depend  to  a  great  extent 
on  the  clinical  history  and  probable  etiology  of  a  given 
case.  The  term  gangrene  of  the  lung  does  not  represent  a 
distinct  entity  except  in  some  acute  cases.    It  is  a  descrip- 


THORACIC  VISCERA  391 

tive  term  pointing  clinically  to  the  existence  of  putrid  spu- 
tum which  is  present  at  some  time  or  other  during  the 
course  of  most  cases  of  suppuration  without  apparently 
affecting  the  course  of  the  disease. 

The  more  common  causes  of  lung  suppuration  are : 

1.  Pneumonia  and  influenza. 

2.  Aspiration  of  foreign,  especially  septic,  material  dur- 
ing operations  under  general  anesthesia. 

3.  Accidental  aspiration  of  foreign  bodies,  especially 
in  children. 

4.  Fibroid  conditions  of  the  lung,  whether  due  to  syphil- 
is, tuberculosis,  or  other  chronic  forms  of  pneumonia. 

Old  cases  of  encapsulated  empyema  are  often  disguised 
clinically  as  cases  of  lung  abscess. 

Two  essential  pathological  changes  are  present  in  prac- 
tically all  cases  of  lung  suppuration.  In  the  first  place 
there  is  an  infiltration  or  consolidation  of  the  lung  of  vary- 
ing extent.  Secondly,  imbedded  in  the  infiltrated  lung  are 
one  or  more  cavities.  These  may  be  multiple,  bronchi- 
ectatic  dilatations,  or  a  small  number  of  irregular  necrotic 
cavities. 

The  examination,  therefore,  has  for  its  object  the  demon- 
stration of  a  pulmonary  infiltration  or  of  a  cavity  in  the 
lung,  or  both,  and  there  are  few  thoracic  conditions  in 
which  it  is  more  instructive.  In  abscess  of  the  lung  the 
symptoms,  such  as  expectoration  of  the  characteristic  spu- 
tum, take  precedence  over  the  physical  signs  which  are 
usually  not  pronounced.  It  is  almost  the  exception  to 
elicit  the  physical  signs  of  a  cavity,  because  the  cavity 
is  usually  imbedded  in  the  infiltrated  lung.  The  infiltra- 
tion, on  the  other  hand,  often  gives  no  signs  because  it 
may  be  scattered  or  of  small  extent  or  masked  by  aerated 
lung. 

A  typical  form  of  lung  abscess  is  that  due  to  aspiration. 


392  U.  S.  ARMY  X-RAY  MANUAL 

The  findings  vary  depending  on  the  evolution  of  the  process. 
In  the  early  weeks  after  the  onset,  there  is  often  consider- 
able pneumonic  infiltration  which  may  involve  a  whole  lobe 
or  a  part  of  it,  the  shadow  being  usually  denser  than  that 
of  lobar  pneumonia.  At  even  this  early  stage  of  the  dis- 
ease a  cavity  varying  from  %  to  l^/^  inches  in  diameter 
can  usually  be  demonstrated  within  the  infiltrated  area. 

One  must,  however,  be  prepared  to  make  the  diagno- 
sis of  lung  abscess  although  a  cavity  is  not  shown  on  the 
plate.  In  a  case  presenting  the  history  and  symptoms  of 
lung  suppuration,  the  discovery  of  a  pneumonic  infiltration 
will  warrant  the  diagnosis.  It  may  occur  in  any  of  the 
lobes  and  may  be  so  small  in  extent  as  to  be  barely  visible. 
This  occurs  especially  during  a  period  of  either  temporary 
or  permanent  improvement.  As  the  disease  progresses  re- 
peated examinations  will  often  show  an  increase  in  the  ex- 
tent and  density  of  the  shadows,  thus  making  absolute 
what  was  previously  a  doubtful  diagnosis. 

Abscess  Cavities. — The  term  abscess  of  the  lung  naturally 
brings  to  the  mind  the  notion  of  a  cavity  within  it.  While 
a  section  of  the  lung  would  in  every  case  show  one  or  more 
cavities,  the  x-rays  will  disclose  them  only  when  they  are 
sufficiently  large,  favorably  situated,  and  partly  filled  with 
fluid.  Abscess  cavities  have,  as  a  rule,  a  punched-out  ap- 
pearance due  to  the  contrast  between  the  air  in  them  and 
the  dense  lung  about  them.  As  they  are  usually  partially 
filled  with  fluid,  they  show,  in  the  upright  position,  a 
horizontal  level  which  is  surmounted  by  air,  an  appearance 
which  is  pathognomonic.  At  times  the  fluid  level  is  seen 
without  other  evidence  of  a  cavity.  The  fluid  level  shifts 
on  change  of  position,  and  the  size  and  shape  of  the 
cavity  in  the  vertical  diameter  may  be  determined. 

Cavities  are  nearly  always  circular.  In  most  cases  only 
one  is  seen,  especially  when  it  is  large.     Of  the  smaller 


THORACIC  VISCERA 


393 


ones  several  may  be  noted  grouped  together  in  one  region. 
The  plate  rarely  shows  a  distinct  capsule  about  them,  ex- 
cept in  the  very  old  ones.     In  these  cases  it  is  unusual  to 


Fig.  180.     Lateral  recumbent  position. 

Especially  useful  for  the  demonstration  of  shifting  fluid  levels. 
Good  method  to  demonstrate  abscess  cavity. 

The  affected  side  should  be  uppermost;  the  focus  of  tube,  as 
nearly  as  can  be  determined,  opposite  area  of  lesion.  The  patient 
can  hold  the  plate  himself  (shown  in  this  illustration)  or  the  plate 
may  be  held  against  his  chest  by  the  screen  carrier.  Direction  of 
rays  need  not  be  always  dorsoventral,  as  shown  in  this  illustration, 
but  may  be  ventrodorsal,  depending  upon  what  is  most  desirable  in  a 
given  case. 

find  them  surrounded  by  dense  layers  of  connective  tis- 
sue as  is  seen  in  old  tuberculous  cavities. 

The  absence  of  a  cavity  in  a  presumed  case  of  pulmonary 


394  U.  S.  AR:\IY  X-RAY  MANUAL 

suppuration  should  not  be  affirmed  from  a  single  examina- 
tion. A  cavity  full  to  repletion  may  cast  a  shadow  indis- 
tinguishable from  the  surrounding  infiltration.  A  later 
examination  after  expectoration  may  reveal  it  partly  empty. 
It  is  remarkable  with  what  fidelity  a  good  plate  will  mirror 
forth  even  the  faintest  level  of  fluid  in  an  abscess  cavity. 
The  cavity  may  be  situated  deep  down  in  the  costophrenic 
sinus  or  be  partly  hidden  by  the  heart.  In  these  cases 
examination  in  the  lateral  recumbent  position  (Fig.  180) 
may  have  to  be  resorted  to.  A  cavity  not  seen  in  the  ordi- 
nary dorsoventral  position  may  occasionally  be  visible  in 
the  ventrodorsal  or  in  one  of  the  oblique  positions.  Doubt- 
less the  smaller  and  deeper  ones  will  elude  the  most  careful 
examination. 

Another  type  of  suppurative  lung  disease  is  that  result- 
ing from  the  various  forms  of  indurative  pneumonia,  usu- 
ally of  long  standing,  in  w^hich  there  is  a  formation  of 
multiple  small  bronchiectases.  Although  larger  bronchi- 
ectatic  cavities  may  develop,  usually  they  are  too  small  to 
be  noted  on  the  plate.  Under  the  circumstances  diag- 
nosis must  be  made  from  the  presence  of  an  infiltration, 
which  is  often  lobar  in  distribution,  very  dense  and  usu- 
ally situated  in  the  lower  lobes.  At  times  when  they  are 
empty,  the  numerous  small  bronchiectases  will  give  to  the 
lung  a  honeycomb  appearance.  These  cases  are  often  as- 
sumed clinically  to  be  chronic  bronchitis,  tuberculosis  or 
persistent  pneumonia.  The  clinical  history,  together  with 
the  x-ray  findings  of  a  pneumonic  process,  will  show  them 
to  be  chronic  nontuberculous  bronchiectases. 

Repeated  examinations  will  throw  light  on  some  of  the 
changes  which  are  taking  place  in  the  lung  during  the 
evolution  of  abscess.  Exacerbation  in  the  fever  and  cough 
may  be  seen  to  be  coincident  with  an  increase  in  the  area  of 
pneumonic  consolidation.     Or,  as  the  result  of  the  over- 


THORACIC  VISCERA  395 

flow  of  the  secretion  of  a  cavity,  a  septic  bronchopneu- 
monia of  a  lower  lobe  may  rapidly  develop.  The  changes 
in  the  size  and  contents  of  the  cavities  can  be  noted. 

Abscess  of  the  lung  is  subject  to  deceptive  remissions, 
and  these  slight  infiltrations  become  the  starting  points  for 
renewed  infection.  The  marked  thoracic  deformity  and 
displacement  of  the  heart  and  mediastinum  so  commonly 
seen  in  tuberculosis  are  absent  in  abscess. 

The  x-ray  examination  is  of  great  value  to  the  surgeon. 
In  the  first  place  it  determines  the  location  of  the  process, 
which  must  precede  any  surgical  intervention.  On  this  and 
on  the  extent  of  the  disease  will  depend  the  type  of  opera- 
tion to  be  performed.  The  size  and  position  of  the  cavity 
with  respect  to  the  chest  w^all  will  often  decide  whether 
the  operation  shall  consist  merely  of  incision  and  drain- 
age, which  at  best  is  only  palliative  in  most  cases,  or 
whether  an  actual  lobectomy  is  advisable.  The  presence 
or  absence  of  pleural  adhesions  may  sometimes  be  ascer- 
tained. After  operation  the  examination  is  of  no  less  im- 
portance. It  will  indicate  the  success  of  the  drainage  or 
the  completeness  of  the  removal  of  the  diseased  lobe.  It 
is  also  a  guide  to  the  success  of  measures  adopted  for  the 
obliteration  of  the  dead  space  produced  by  the  operation. 

Differential  Diagnosis. — It  is  not  necessary  to  go  into  a 
differential  diagnosis  between  the  appearance  of  lung  ab- 
scess and  other  thoracic  conditions  with  which  it  might  be 
confused.  The  clinical  history  will  usually  serve  to  dis- 
tinguish them.  There  is,  however,  at  times  some  difficulty 
in  differentiating  abscess  from  tuberculosis.  The  follow- 
ing points  of  distinction  are  suggested,  although  they  will 
not  always  apply.  An  infiltration  or  a  cavity  in  a  lower 
lobe  with  no  coincident  process  in  the  apex  is  probably  not 
tuberculous.  In  cases  of  upper  lobe  infiltration  the  diffi- 
culty may  be  greater.    Homogeneous  consolidations  of  the 


396  U.  S.  ARMY  X-RAY  IMANUAL 

lobar  type  are  more  apt  to  be  abscesses,  especially  if  they 
contain  a  cavity  with  a  fluid  level.  The  coarse  bands  of 
connective  tissue,  extending  to  the  hilum,  and  calcareous 
deposits,  so  frequently  found  in  chronic  tuberculosis,  are 
rare  in  abscess. 

Tuberculous  cavities  are,  as  a  rule,  different  in  appear- 
ance from  abscess  cavities.  They  usually  contain  no  fluid. 
Tuberculous  cavities  occur  usually  in  the  upper  lobe  and 
are  uncommon  at  the  bases.  Of  course,  tuberculous  cavities 
may  be  secondarily  infected.  In  that  case,  they  are  to  all  in- 
tents and  purposes  abscess  cavities  and  cannot  be  distin- 
guished from  them,  except  perhaps  by  the  character  of  the 
surrounding  infiltration.  Old  cases  of  encapsulated  empy- 
ema are  frequently  mistaken  clinically  for  lung  abscess. 

New  Growths  of  the  Lungs. — New  growths  of  the  lungs 
may  be  divided  into  two  types,  metastatic  and  primary. 

Of  metastatic  new  growths  those  most  commonly  encoun- 
tered are  carcinoma  and  sarcoma.  By  means  of  the  x-ray 
examination  alone  it  is  not  possible  to  distinguish  them. 
The  earliest  metastases  appear  as  faint  circular  homo- 
geneous shadows  a  few  millimeters  in  diameter.  They  are 
irregularly  distributed  throughout  the  lungs  and  are  larger 
in  the  lower  lobes.  The  size  they  attain  varies  with  the 
type  of  the  primary  tumor  and  the  duration  of  the  dis- 
ease. They  may  attain  the  size  of  a  lobe ;  on  the  other 
hand,  even  at  a  late  stage  of  the  disease  the  lungs  may  be 
studded  with  myriads  of  small  metastases.  IMiliary  car- 
cinosis may  be  difBcult  to  differentiate  from  some  forms  of 
tuberculosis.  The  x-ray  examination  will  reveal  metastases 
before  the  clinical  examination  will  discover  them.  For 
this  reason  it  is  important  to  ray  the  chest  prior  to  opera- 
tion of  primary  tumor,  especially  sarcoma,  in  other  parts 
of  the  body. 

Primary  new  growths  occur  in  two  forms,  the  true  pul- 


THORACIC  VISCERA  397 

monary  and  the  mediastinal  tumors.  By  the  x-ray  examin- 
ation, just  as  by  the  clinical,  it  is  often  impossible  to  de- 
cide whether  a  neoplasm  arises  in  the  lung  or  mediastinum, 
because  mediastinal  growths  as  they  increase  in  size  may 
invade  the  lung.  In  their  earlier  stage  this  distinction  may 
be  made. 

Prim.ary  carcinoma  of  the  lung  assumes  two  forms,  the 
so-called  bronchial  carcinoma  and  the  lobar  carcinoma. 
The  former  begins  usually  in  one  of  the  larger  bronchi  and 
casts  a  dense  shadow  extending  a  variable  distance  from 
the  root  of  the  lung.  Numerous  secondary  tumors  de- 
velop by  extension  along  the  bronchial  system,  producing 
a  network  of  small  shadows  along  the  bronchial  tree.  In 
lobar  carcinoma  there  is  found  a  dense  shadow  which  oc- 
cupies a  part  or  all  of  a  lobe.  This  seems  to  occur  more 
frequently  in  the  upper  lobes.  In  all  forms  of  primary 
growths  the  intercostal  spaces  are  frequently  narrowed, 
and  the  heart  and  mediastinum  are  apt  to  be  drawn  over 
to  the  affected  side,  unless  prevented  by  a  hydrothorax. 

It  should  be  remembered  in  the  diagnosis  of  pulmonary 
neoplasms  that  the  shadows  have  not  a  typical  arrange- 
ment, as  in  tuberculosis  and,  therefore,  in  order  to  avoid 
error,  the  clinical  data  should  be  fully  utilized.  Not  un- 
commonly a  neoplasm  is  completely  masked  by  a  pleural 
effusion,  so  that  a  diagnosis  cannot  be  made  until  after 
aspiration  of  the  chest. 

Mediastinal  New  Growths. — Under  this  heading  are  in- 
cluded the  various  lymphomata,  Hodgkin's  disease,  lym- 
phosarcoma, and  carcinoma  and  sarcoma.  Only  to  a  lim- 
ited extent  is  it  possible  to  distinguish  these  from  each 
other. 

The  masses  of  enlarged  lymph  nodes  in  Hodgkin's  dis- 
ease produce  rather  faint  shadows  at  the  roots  of  the  lungs. 
These  extend  a  variable  distance  into  the  pulmonary  tissue. 


398  U.  S.  ARMY  X-RAY  MANUAL 

Usually  the  shadow  has  an  irregularly  lobulated  border 
which  is  well  demarcated.  At  times  small  secondary  nod- 
ules are  seen  elsewhere  in  the  lungs. 

In  the  other  varieties  of  new  growths  a  dense  shadow 
extends  outward  from  the  mediastinum,  usually  on  both 
sides.  This  shadow  is  confluent  with  that  of  the  heart  and 
of  the  aorta,  although  on  the  fluoroscope  it  can  usually 
be  distinguished  from  it.  It  may  occupy  only  the  upper 
mediastinum,  as  in  the  case  of  a  substernal  thyroid,  or 
only  the  region  of  the  hilum  of  the  lungs.  Its  outline  may 
be  smooth  or  lobulated,  straight  or  convex.  The  shadow 
is  homogeneous  and  shows  no  calcareous  areas  as  in  tuber- 
culosis. Occasionally  the  growth  can  be  seen  radiating 
in  all  directions  into  the  lung  tissue.  Small  outlying 
metastases  may  also  be  seen  in  the  lung.  In  the  oblique 
position  the  relation  of  the  growth  to  the  trachea  and 
esophagus  can  be  studied,  and  pressure  by  the  growth  on 
these  structures,  or  their  invasion  by  it,  observed.  In  the 
dorsoventral  position  a  narrowing  of  the  caliber  of  the 
trachea  may  be  seen  or  a  downward  or  lateral  displace- 
ment of  the  arch  of  the  aorta.  On  fluoroscopic  examina- 
tion, in  the  case  of  compression  of  a  large  bronchus,  the 
so-called  bronchostenotic  sign  may  be  observed.  This  con- 
sists in  a  displacement  of  the  mediastinum  toward  the 
side  of  the  stenosis  on  deep  inspiration.  Mediastinal 
growths  favorably  placed  with  regard  to  the  heart  or  the 
aorta  will  show  a  transmitted  pulsation.  This  is  very 
difficult  to  distinguish  from  that  of  a  pulsating  aneurysm 
and,  for  this  reason,  has  little  value  in  a  differential  diag- 
nosis. 

In  conclusion,  it  should  be  emphasized  that  it  is  hazard- 
ous to  venture  a  diagnosis  of  mediastinal  growth  solely  on 
the  basis  of  moderate  enlargement  of  the  hilum  structures. 
Such  a  condition  is,  in  the  vast  majority  of  cases,  due  to 


THORACIC  VISCERA  399 

the  enlargement  of  the  bronchial  lymph  nodes,  regularly 
found  in  adults. 

Tumors  of  the  ribs  and  spine  occasionally  cast  shadows 
in  the  chest  which  must  be  distinguished  from  intrathoracic 
conditions.  Thus,  rib  sarcomata  may  produce  circum- 
scribed shadows  of  uniform  density,  which  may  simulate 
pulmonary  new  growths,  or,  if  they  occur  near  the  pe- 
riphery of  the  chest,  may  resemble  encapsulated  effusions. 
Careful  study  of  the  rib  structure,  sometimes  in  the  oblique 
position,  or  stereoscopy  will  reveal  an  absence  of  the  rib 
at  the  site  of  the  shadow.  Pott's  abscess  of  the  vertebrae 
must  occasionally  be  taken  into  consideration  in  the  in- 
terpretation of  intrathoracic  shadows. 

Aneurysm  of  the  Thoracic  Aorta. — In  the  diagnosis  of 
aortic  aneurysm  the  x-ray  is  recognized  by  the  clinician 
as  the  most  valuable  method  of  examination.  Fluoroscopy 
is  far  superior  to  radiography  because  we  are  dealing  with 
an  organ  in  motion.  The  plate  merely  furnishes  a  per- 
manent and  graphic  record  for  comparison  with  later  ex- 
aminations. The  patient  should  be  fluoroscoped  in  sev- 
eral directions.  The  dorsoventral  position  furnishes  the 
most  information.  The  first  oblique  position  shows  the  en- 
croachment upon  the  posterior  mediastinum  by  an  aneurysm 
of  the  descending  aorta ;  the  second  oblique  position  brings 
out  more  clearly  an  aneurysm  in  the  ascending  aorta  and 
may  show  the  extent  of  an  aneurysm  of  the  descending 
aorta.  A  true  lateral  view,  which  is  feasible  in  a  small 
number  of  cases  only,  is  of  value  in  determining  the 
anteroposterior  enlargement  of  the  aorta. 

Though  pulsation  is  not  an  absolutely  reliable  sign  in  all 
eases,  its  presence  or  absence,  its  character,  whether  ex- 
pansile or  transmitted,  will  aid  in  the  diagnosis.  Expansile 
pulsation  (pulsation  in  all  directions)  suggests  aneurysm, 
especially  of  the  fusiform  variety.     Transmitted  pulsation 


400  U.  S.  ARMY  X-RAY  MANUAL 

(pulsation  in  one  direction)  occurs  when  a  mediastinal 
tumor  is  in  close  contact  with  the  aorta.  In  this  condi- 
tion the  excursions  of  the  aorta  move  the  tumor,  thus  giv- 
ing the  appearance  of  pulsation.  On  the  other  hand,  very- 
slight  pulsation  or  even  its  complete  absence  does  not  ex- 
clude aneurysm.  This  is  especially  true  of  the  sacculated 
variety  on  account  of  the  thickening  of  the  sac. 

Aneurysms  may  involve  any  portion  of  the  aorta,  but  in 
their  order  of  frequency  are  seen  as  follows : 

1.  Aneurysms  of  the  ascending  aorta  cast  their  shadows 
almost  entirely  to  the  right  of  the  spine  and  lie  near  the 
anterior  chest  wall. 

2.  Aneurysms  of  the  arch  lie  in  the  upper  part  of  the 
mediastinum,  generally  in  the  midline,  but  may  extend  to 
the  right  or  left  according  to  the  portion  of  the  arch  that 
is  involved.     They  also  are  nearer  the  anterior  chest  wall. 

3.  Aneurysms  of  the  descending  aorta  are  almost  en- 
tirely to  the  left  of  the  midline  and  lie  nearer  the  posterior 
wall. 

The  shadow  of  the  aneurysm  is  of  necessity  confluent 
with  that  of  the  aorta.  It  is  even  in  contour,  rather  con- 
vex and  usually  shows  no  lobulations. 

The  shadow  cast  by  an  aneurysm  of  the  ascending  aorta 
and  arch  is  as  dense  as  that  of  the  heart,  because  both  are 
situated  in  the  same  vertical  plane.  The  shadow  cast  by 
an  aneurysm  of  the  descending  aorta  is  less  dense  in  the 
dorsoventral  position  because  it  is  not  in  the  same  verti- 
cal plane  as  that  of  the  heart  shadow,  being  situated  more 
dorsally. 

The  large  aneurysms  are  usually  fusiform.  The  smaller 
ones  are  either  sacculated  or  fusiform.  As  a  general  rule, 
those  of  the  arch  are  more  frequently  sacculated;  those 
of  the  descending  and,  to  a  lesser  extent,  those  of  the  as- 
cending, are  more  frequently  of  the  fusiform  variety.     It 


THORACIC  VISCERA  401 

is  important  to  remember,  however,  that  there  are  dilata- 
tions of  the  aorta  which  are  not  aneurysms  in  the  true  sense 
of  the  word.  This  fact  must  be  borne  in  mind  when  ex- 
amining adults  beyond  middle  age,  because  in  them  a  mod- 
erate enlargement  and  lengthening  of  the  aorta  are  com- 
mon. This  is  shown  usually  by  an  increased  prominence 
in  the  upper  part  of  the  chest  to  the  left  of  the  spine,  as 
the  aorta  turns  downward  and  backward.  In  cases  of 
atheroma,  the  aorta  may  be  uniformly  dilated  throughout 
its  entire  course.  In  such  cases  it  extends  to  the  right  of 
the  sternum,  the  arch  is  prominent  and  the  descending  por- 
tion may  be  seen  as  a  faint  shadow  to  the  left  of  the  spine. 
This  condition  is  frequently  associated  with  hypertrophy 
of  the  left  ventricle  and  aortic  insufficiency.  On  the  other 
hand,  enlargement  of  the  heart  is  generally  not  associated 
with  aneurysm. 

The  most  common  difficulty  encountered  is  the  differentia- 
tion between  aneurysm  and  mediastinal  tumors.  The  fol- 
lowing points  may  be  helpful : 

The  shadow  caused  by  an  aneurysm  is  usually  denser 
than  that  of  a  tumor. 

Large  aneurysms  of  the  aorta,  especially  of  the  first  por- 
tion, displace  the  heart  downward  and  often  to  the  left. 
Tumors  nearly  always  displace  the  heart  laterally. 

Large  aneurysms  of  the  arch  and  descending  aorta  dis- 
place the  trachea  and  esophagus,  while  tumors,  except 
intrathoracic  thyroid,  envelop  them. 

Fluoroscopy  in  the  oblique  positions  will  help  to  estab- 
lish the  relation  of  the  aneurysm  to  the  heart,  aorta  and  the 
other  thoracic  organs,  which  cannot  otherwise  be  done.  In 
this  manner,  we  can  sometimes  recognize  the  normal  con- 
tour of  the  aorta  within  a  shadow  which  is  suspicious  of 
aneurysm  and  thus  establish  the  diagnosis  of  tumor  rather 
than  of  aneurysm. 


402  U.  S.  ARMY  X-RAY  MANUAL 

Growth  of  the  aneurysm  may  produce  changes  in  the 
adjacent  viscera  or  in  the  spine.  These  changes  are  en- 
tirely mechanical  and  due  to  pressure. 

Pressure  upon  the  esophagus  may  cause  displacement 
and  obstruction,  which  is  at  times  almost  complete.  In 
case  an  aneurysm  is  very  large,  it  is  advisable  to  examine 
the  esophagus  with  the  aid  of  a  barium  mixture  so  as  to 
determine  the  presence  of  esophageal  obstruction,  or  com- 
pression. Often  the  fluoroscope  would  show  pressure  upon 
the  esophagus  long  before  the  patient  noticed  difficulty  in 
swallowing. 

Pressure  upon  a  bronchus  may  cause  bronchostenosis 
or  even  atelectasis.  In  such  cases  the  fluoroscope  shows  in 
the  lung  field  supplied  by  the  bronchus  a  darker  area  which 
does  not  become  lighter  upon  deep  inspiration.  Occa- 
sionally the  severe  spinal  symptoms  associated  with  an- 
eurysm are  due  to  actual  erosion  of  one  or  more  vertebrae 
from  pressure. 

X-Ray  Examination  of  the  Heart. — The  method  of 
choice  in  the  roentgen  study  of  the  heart  is  fluoroscopy. 
The  reason  for  this  is  that  the  heart  is  an  organ  in  con- 
tinual motion,  and  a  study  of  its  movement  is  essential  to 
a  proper  interpretation  of  the  shadows.  The  plate  gives 
such  a  distorted  image  of  the  heart  that  it  is  not  only 
valueless  but  may  give  rise  to  entirely  erroneous  deduc- 
tions. Of  all  the  methods,  orthodiagraphy,  combining  as 
it  does  direct  observation  and  a  true  graphic  image  of  the 
heart,  is  most  valuable.  A  plate  made  at  a  distance  of  six 
feet  (teleroentgenogram),  although  not  as  serviceable,  is 
of  value  for  determining  heart  size. 

The  cardiovascular  shadow  is  composed  of  a  number  of 
curves,  two  on  the  right  side  and  three  or  four  on  the 
left,  which  represent  the  following  parts: 


THORACIC  VISCERA 


403 


The  right  upper  curve  represents  superior  cava  or,  oc- 
casionally, the  ascending  aorta. 

The  right  lower  curve  represents  the  right  auricle. 

The  left  upper  curve  represents  the  arch  of  the  aorta. 

The  left  middle  curve  rep- 
resents the  pulmonary  artery. 

The  left  lower  curve  repre- 
sents the  left  ventricle. 

Occasionally  the  curve  of 
the  left  auricle  is  seen  be- 
tween the  middle  and  lower 
curves.     (Fig.  181.) 

The  shape  and  extent  of 
these  shadows  which  form  the 
contour  of  t  h  e  heart  are 
more  or  less  constant  though 
they  are  subject  to  slight 
physiological  variations.  At 
times  these  shadows  are  ill- 
defined  and  a  study  of  their 
pulsations  may  be  necessary 
to  distinguish  them.  The  lat- 
ter differ  both  as  to  their  am- 
plitude and  their  time  phase. 
Thus  the  right  lower  curve 
of  the  auricle  shows  a  very 
faint  pulsation  presystolic  in 
time.  The  curve  of  the  left 
ventricle  has  the  widest  pul- 
sation systolic  in  time.  The  aortic  and  pulmonary  curves 
show  a  moderate  expansion  synchronous  with  the  contrac- 
tion of  the  ventricles.  The  left  auricular  appendage  is 
poorly  seen  the  ordinary  position  and  shows  only  a  slight 
presytolic  undulation. 


Fig.  181.  Normal  heart  (or- 
thodiogram). 

(a)  Vena  cava  superior,  (b) 
Kight  auricle,  (e)  Descending 
arch  of  aorta,  (d)  Pulmonary- 
artery,  (e)  Left  auricle  (oc- 
casionally seen),  (f)  Left  ven- 
tricle. The  right  ventricle  is 
never  seen  in  this  position. 

MIR — Longest  distance  be- 
tween the  median  line  and  the 
right  border.  ML — Longest  dis- 
tance between  the  median  line 
and  the  left  border.  L — Longi- 
tudinal diameter.  ML  +  ME 
equals  the  transverse  diameter, 
T. 


404  U.  S.  ARMY  X-RAY  MANUAL 

Normal  Variations  of  the  Heart  Shadow. — The  configura- 
tion of  the  heart  shadow  is  determined  to  a  considerable 
extent  by  the  obliquity  of  its  long  axis.  But  this  is  fre- 
quently affected  by  extrinsic  factors.  Thus  it  will  vary 
with  the  type  of  the  thorax,  being  more  horizontal  in  the 
broad-chested  and  more  oblique  or  vertical  in  the  narrow- 
chested  or  asthenic  individual.  Adiposity  or  gaseous  dis- 
tention of  the  intestines  may  rotate  the  heart  into  a  more 
horizontal  position  and  may  mold  it  so  that  it  will  simulate 
a  hypertrophy.  In  the  aged  the  heart  is  less  oblique  in 
position  and  its  apex  becomes  blunted.  There  is  some 
variation  in  the  prominence  of  the  individual  curves.  The 
pulmonary  artery  is  at  times  abnormally  large  without 
any  evidence  of  cardiac  disease.  The  arch  of  the  aorta, 
especially  in  persons  beyond  the  age  of  forty,  is  frequently 
prominent,  and  this  should  not  be  looked  upon  as  evidence 
of  serious  disease.  It  is,  therefore,  important  in  estimating 
the  significance  of  a  particular  cardiogram  to  keep  in  mind 
these  normal  variations. 

Heart  Size. — By  means  of  the  x-ray  approximate  figures 
of  the  heart  size  have  been  determined  in  a  large  num- 
ber of  healthy  individuals.  These  have  been  formulated 
in  standard  tables. 

The  dimensions  most  commonly  used  are  conveniently 
designated  by  the  values  ML  and  MR,  indicating  respec- 
tively the  greatest  distance  of  the  left  and  right  borders 
from  the  midline.  The  sum  of  these  two  values  represents 
the  width  or  transverse  diameter  of  the  heart,  T.  A  third 
dimension,  L,  representing  the  longitudinal  diameter  is 
also  frequently  used.  It  extends  from  the  angle  formed 
by  the  right  auricle  and  vessels  to  the  apex  (Fig.  182).  A 
study  of  tables  shows  that  the  size  of  the  heart  varies  with 
the  height  and  weight  of  the  individual  and  also  with  the 
sex,  the  figures  for  the  female  being  slightly  smaller.     In 


THORACIC  VISCERA  405 

a  general  way  the  relation  of  MR:  ML  is  as  1:2.  In  ap- 
plying these  tables,  the  height  of  the  individual  must  be 
determined  and  the  dimensions  of  the  heart  compared  with 
the  normal  figures  for  a  subject  of  the  same  height.  In 
determining  whether  a  given  case  exceeds  the  normal,  a 
difference  of  V2  to  1  cm.  in  the  transverse  diameter  from 
the  normal  is  permitted. 

Note. — At  the  end  of  this  chapter  the  reader  will  find  a 
detailed  description  of  the  method  used  by  the  cardio- 
vascular service. 

Dilatation  and  Hypertrophy  of  the  Heart. — A  dilatation 
of  the  cardiac  cavities  results  in  an  increase  in  the  size 
and  prominence  of  the  contour  together  with  an  increase  in 
the  values  ML  and  MR.  In  the  case  of  the  left  ventricle 
this  results  in  a  more  horizontal  position  of  the  heart,  so 
that  it  acquires  a  shape  which  has  been  compared  to  that 
of  an  egg.  The  ventricular  border  formes  a  sharp  angle 
near  the  pulmonary  curve  and  the  apex  is  blunted.  A  di- 
latation of  the  right  ventricle  by  itself  produces  no  enlarge- 
ment of  the  heart,  but  it  changes  its  conformation  by  di- 
lating in  an  upward  direction,  so  that  the  conus  arteriosus 
and  its  right  auricular  attachment  are  displaced  upward. 
The  heart  thus  acquires  a  more  vertical  and  globular  aspect. 
A  marked  enlargement  to  the  right  is  usually  due  to  a 
coincident  dilatation  of  the  right  auricle.  It  is  well  to 
bear  in  mind,  however,  that  whereas  clincally  a  distinct 
increase  in  absolute  heart  dullness  to  the  right  may  be 
found,  the  x-ray  frequently  in  such  cases  shows  the  right 
heart  border  to  be  in  its  normal  position. 

A  pure  hypertrophy  of  the  left  ventricle  is  readily  recog- 
nized. The  silhouette  is  the  same  as  described  above  in 
cases  of  dilatation  of  the  left  ventricle,  except  that  there 
is  no  increase  in  the  size  of  the  heart.  The  pulsation  is 
deliberate  and  of  increased  amplitude.     The  greatest  en- 


406 


U.  S.  ARMY  X-RAY  MANUAL 


largement  to  the  left  is  found  in  cases  of  aortic  insufficiency, 
in  the  hypertensile  form  of  chronic  nephritis  and  in  ad- 
vanced mitral  disease;  enlargement  to  the  right  is  most 
often  found  in  all  forms  of  decompensation  and  in  con- 
genital heart  disease. 
Displacement  of  the  Heart. — This  is  readily  recognized. 


Fig.  182.  Mitral  insuffi- 
ciency: Entire  cardiac  shadow 
enlarged  (except  right  vena 
cava.  The  prominence  of  the 
pulmonary  artery  is  not  due  to 
enlargement  of  the  artery  itself 
but  to  displacement  by  the  en- 
larged heart. 


Fig.  183.  Pure  mitral  ste- 
nosis: Marked  enlargement  of 
the  left  auricle  (e).  Heart  oth- 
erwise not  enlarged.  Pulmo- 
nary artery  (d)  may  be  slight- 
ly enlarged.  Aortic  arch  not 
shown  on  this  sketch. 


One  of  the  most  frequent  causes  is  chronic  tuberculosis  in 
which  the  heart  is  usually  drawn  over  by  pleural  or  medias- 
tinal adhesions  to  the  side  containing  the  oldest  lesions. 
Pleural  effusions  frequently  displace  the  heart  to  the  op- 
posite side.  This,  however,  is  not  an  invariable  rule,  as 
the  heart  may  occasionally  be  in  its  normal  position  even 
in  the  presence  of  a  large  effusion.  In  kypho-scoliosis  the 
heart  is  frequently  displaced  and  rotated;  on  the  other 
hand  this  does  not  invariably  result,  as  the  heart  may  be 


THORACIC  VISCERA 


407 


0 

y* 


normally  situated  in  spite  of  marked  thoracic  deformity. 
In  emphysema  and  asthma  the  heart  is  often  hypoplastic 
and  its  apex  depressed  below  the  sixth  interspace  so  that 
it    acquires    the    shape    of   a 
drop    heart.      The    most    ex- 
treme   displacement    may   be 
found  in   eventration  of  the 
diaphragm,  so  much,  in  fact, 
that  a  dextrocardia  is  closely 
simulated,  when  the  eventra- 
tion   is    on    the    left    side,    a 
more  frequent  position  than 
on  the  right. 

Valvular  Lesio7is. — The  me- 
chanical changes  produced  by 
valvular  lesions  and  the  re- 
sulting alterations  in  the 
cardiac  cavities  are  faithfully 
reflected  in  the  heart  shadow. 
Each  cardiac  lesion  or  its 
combination  with  others  has 
a  more  or  less  characteristic 
silhouette.  Some  of  these 
are  represented  in  the  accom- 
panying figures.  Figs.  182- 
184.  Of  particular  impor- 
tance is  the  recognition  of  the 
early  stages  of  mitral  disease. 
The  earliest  signs  noted  are  a 
slight  enlargement  to  the  left, 

an  increased  prominence  of  the  pulmonary  artery  and 
of  the  left  auricle,  and  a  tendency  toward  globular 
shape. 

Nephritis  and  Arterial  Hypertension. — In  their  early 


Fig.  184.  Aortic  insuflBLcien- 
ey:  Left  ventricle  (f )  marked- 
ly enlarged.  Left  auricle  (e) 
and  pulmonary  artery  (d)  little 
affected.  Aortic  arch  (c)  more 
prominent.  (a)  in  this  case, 
represents  ascending  aorta 
masking  vena  cava  superior. 
(a)  and  (c)  are  actually  en- 
larged in  advanced  stages.  In 
the  early  stage  they  are  more 
prominent  because  of  the  in- 
creased volume  of  blood  they 
have  to  carry. 

The  transverse  position  of 
the  heart  is  characteristic  of 
this  condition. 


408 


U.  S.  ARMY  X-RAY  MANUAL 


*^>.. 


*■' 


stages  these  two  conditions  produce  a  hypertrophy  of  the 
left  side  of  the  heart  with  little  or  no  dilatation.  The 
appearance  on  the  screen  is  characteristic.     The  heart  is 

horizontal,  egg-shaped,  and 
is  blunted  at  the  apex.  As 
these  conditions  are  frequent- 
ly combined  with  atheroma  of 
the  aorta,  the  latter  is  usu- 
ally seen  to  be  dilated  and  ir- 
regular in  outline.  (Fig.  185.) 
These  cases  are  frequently 
confused  with  aneurysm, 
owing  to  pulsation  of  the 
aorta ;  this  error  can  be  avoid- 
ed by  noting  the  diffuse  char- 
acter of  the  aortic  dilatation 
and  the  enlargement  of  the 
left  ventrical.  In  the  later 
stages  of  chronic  nephritis 
we  see  evidence  of  failure  of 
the  left  ventricle,  namely,  en- 
largement to  the  right  and 
prominence  of  the  left  auri- 
cle and  of  the  pulmonary  ar- 
tery. The  amplitude  of  the 
pulsation  as  noted  on  the 
screen  bears  no  relation  to 
the  amount  of  hypertrophy  or 
dilatation  nor  to  the  muscular 
strength  of  the  ventricle. 
The  largest  hearts  may  show  practically  no  pulsation,  and 
inferences  as  to  cardiac  failure  should  not  be  drawn  from 
its  absence. 

Angina  Pectoris  and  Anginoid  Pains. — Precordial  pains, 


Fig.  185.  Atheroma  of  the 
Aorta:  (Arterial  hypertension 
—  chronic  nephritis) .  Aortic 
arch  (c)  and  ascending  aorta 
(a)  enlarged.  Pulmonary  ar- 
tery not  seen  on  account  of  ac- 
tual dilatation  of  aorta  to  left 
(shaded  area).  In  this  illustra- 
tion enlargement  of  heart  is 
due  to  chronic  nephritis. 

While  aortic  dilatation  is  fre- 
quently associated  with  cardiac 
enlargement  from  various  con- 
ditions, it  may  occur  unaccom- 
panied by  heart  changes  in  in- 
dividuals beyond  middle  age. 
In  young  individuals,  on  the 
other  hand,  it  is  invariably  as- 
sociated with  cardiac  changes. 


THORACIC  VISCERA  409 

anginoid  in  type,  are  found  in  a  variety  of  heart  and 
arterial  conditions,  the  natnre  of  which  may  be  disclosed 
by  the  x-rays.  In  younger  individuals  they  are  usually 
found  to  be  based  on  the  valvular  diseases,  particularly 
aortic  insufficiency.  In  the  latter,  especially  when  it  is 
consecutive  to  syphilitic  aortitis,  the  examination  will  show 
a  slight  dilatation  of  the  aorta  at  its  origin.  In  older  per- 
sons, angina  may  be  associated  with  atheroma  of  the  aorta 
and  arterial  hypertension.  The  aorta  is  seen  to  be  thick- 
ened, tortuous,  and  dilated  throughout  and  frequently  con- 
tains lime  placques.  A  stud}^  of  the  ascending  aorta  in  the 
second  oblique  position  will  reveal  an  enlargement  of  the 
conus  arteriosus. 

A  large  group  of  cases  of  angina  pectoris  in  adults  is 
primarily  due  to  sclerosis  or  thrombosis  of  the  coronary 
artery.  There  is  no  change  in  the  size  or  shape  of  the 
heart,  and  the  aorta  is  little,  if  at  all,  dilated.  In  these 
cases  the  e:iamination  has  only  a  negative  diagnostic  value 
in  excluding  the  conditions  previously  mentioned.  It  is 
important  to  emphasize  that  in  these  cases  there  may  be  an 
infarction  of  the  heart  muscle  with  extreme  fatty  and 
fibrous  degeneration,  but  with  no  evidence  of  enlargement 
of  the  heart  even  shortly  before  a  fatal  termination. 

So-called  Functional  Heart  Disease. — There  is  a  fairly 
large  number  of  individuals  in  whom  systolic  murmurs  at 
the  apex  of  the  heart  are  heard  and  in  whom  no  other  evi- 
dence of  heart  disease  is  found.  The  question  will  always 
arise  whether  these  persons  have  valvular  lesions  or  whether 
the  murmurs  are  so-called  functional  or  accidental  ones. 
In  such  cases,  the  most  important  factor  to  determine  is 
an  enlargement  of  the  heart.  Examination  may  be  of  de- 
cisive value  in  these  cases.  In  a  case  of  such  a  doubtful 
heart  murmur,  if  no  enlargement  of  the  heart  or  change  in 


410 


U.  S.  ARMY  X-RAY  MANUAL 


its  configuration  are  shown,  it  may  be  fair  to  assume  that 
the  murmur  is  not  valvular  in  origin. 

In  a  similar  way  we  may  have  recourse  to  the  x-ray  in 
a  study  of  the  various  functional  disturbances  resulting 
from  excessive  work  or  nervous  excitement  incidental  to  a 

soldier's    life.      The   marked 

\  '  cardiac   over-action    in   these 

***>*  ^^'j*'  cases  makes  accurate  percus- 

sion  difficult,  and  frequently 
gives  the  impression  of  an  en- 
largement of  the  heart.  This 
enlargement  is  only  appar- 
ent and  is  due  to  the  so- 
called  irradiation  of  the  api- 
cal impulse.  Whatever  the 
mechanism  of  the  cardiac 
weakness  in  these  cases,  the 
x-ray  examination  shows  that 
it  is  not  due  to  a  dilatation  of 
the  heart.  On  the  contrary, 
the  asthenic  individuals  who  are  especially  prone  to  these 
functional  disorders  under  stress  frequently  have  hypoplas- 
tic or  drop  hearts  (Fig.  186). 

Drop  heart  occurs  in  long  chested,  thin  individuals  and 
in  chronic  wasting  diseases.  In  the  latter  it  is  merely  due 
to  the  general  undernourishment  of  the  individual  and  not 
to  any  disease  of  the  heart  itself.  Drop  heart  occurs  fre- 
quently in  the  later  stages  of  tuberculosis  and,  at  one  time, 
was  erroneously  considered  as  pathognomonic  of  tubercu- 
losis and  even  as  a  predisposing  factor  in  this  disease. 

Heart  Function. — Little,  if  any,  deduction  of  value  as 
to  the  function  of  the  heart  muscle  can  be  drawn  from  the 
x-ray  examination.  The  amplitude  of  contraction  of  the 
left  ventricle   is  no  index  of  its  muscular  power.     Nor- 


FiG.  186.    Drop  heart. 


THORACIC  VISCERA 


411 


n: 


// 


mally  two  types  of  contraction  may  be  seen,  a  strong  and 
a  Aveak.  The  former  is  commonly  noted  in  nervous  or 
erethic  individuals  and  in  the  asthenic  or  drop  heart.  The 
latter  is  noted  in  subjects  who  are  less  influenced  by  the 
excitement  induced  by  the  novel  examination.  Fluoro- 
scopic tests  of  function  have  been  barren  of  results.  The 
heart  in  all  individuals  reacts  to  muscular  work  by  a  de- 
crease in  its  size,  w^hich  is  closely  related  to  the  degree  of 
tachycardia.  The  heart  responds  in  a  similar  manner 
to  a  change  from  the  recumbent  to  the  upright  position. 
Cases  of  organic  disease  react  to  these  maneuvers  pretty 
much  as  normal  hearts  do.  As 
far  as  is  known,  dilatation  of 
the  heart  after  exertion  can- 
not be  used  as  a  test  of  func- 
tion, as  it  rarely  if  ever  oc- 
curs under  experimental  con- 
ditions. Little  change  is 
noted  in  the  size  of  the  heart 
after  treatment,  even  though 
there  be  marked  improvement 
of  the  symptoms.  In  cases 
which  show  a  marked  reces- 
sion of  the  cardiac  borders 
after  treatment  the  possibility 

of  the  resorption  of  a  moderate  pericardial  effusion  should 
be  considered. 

Pericarditis. — A  pericardial  effusion,  if  moderate  in 
amount,  results  in  a  general  increase  in  the  size  of  the  heart 
shadow.  Under  these  conditions  the  diagnosis  cannot  be 
made.  It  is  only  when  the  pericardial  sac  is  distended 
with  fluid  that  it  produces  a  characteristic  appearance  (Fig. 
187).  The  heart  assumes  a  flask  shape  and  extends  upward 
to  the  first  or  second  rib  and  also  into  the  right  chest, 


Fig.  187.  Large  pericardial 
effusion:  Heart  shadow  is  en- 
larged laterally  and  upward,  en- 
croaching upon  aorta.  Contour 
divisions  are  absent. 


412  U.  S.  ARMY  X-RAY  MANUAL 

where  it  frequently  occupies  as  much  space  as  in  the  left. 
The  heart  contours  are  long ;  the  pulsations  are  usually  not 
visible,  although  occasionally  a  diffuse  impulse  may  agi- 
tate the  whole  mass. 

In  advanced  myocarditis  the  cardiac  shadow  is  some- 
what similar  to  that  of  pericardial  effusion.  The  distin- 
guishing features  in  this  condition  are  that  the  cardiac 
silhouette  is  more  triangular  in  shape,  does  not  extend  as 
much  to  the  right,  and  does  not  encroach  upon  and  oblit- 
erate the  aortic  shadow. 

Adhesions  between  the  pericardium  and  pleura  are  fre- 
quently seen  as  small  pointed  projections  extending  out  to 
the  surface  of  the  heart.  An  obliteration  of  the  pericar- 
dium can  only  be  diagnosed  if,  in  addition,  there  are  pleuro- 
pericardial  adhesions.  Under  these  circumstances,  on  deep 
inspiration,  with  each  contraction  of  the  heart  the  left 
diaphragm  may  be  pulled  up  forcibly.  This  corresponds  to 
what  is  clinically  known  as  Broadbent's  sign. 

Method  of  Heart  Measurement. — (Adopted  by  the  Car- 
diovascular Service.)  Various  attempts  to  correlate  heart 
measurements  with  pathological  conditions  have  been 
made.  Considerable  caution  in  this  connection  may  be 
advised  for  two  reasons :  first,  there  is  no  very  definite 
relation  between  the  size  of  an  organ  and  its  functional 
condition;  second,  the  errors  due  to  unusual  position  of 
heart  or  bad  apparatus  adjustment  are  such  as  to  make 
the  measurements  themselves  somewhat  uncertain. 

At  the  Army  Medical  School  a  method  is  used  at  present, 
based  on  the  tables  of  Dr.  C.  R.  Bardeen.  For  this  reason 
the  tables  and  the  following  brief  note  as  to  the  method  are 
inserted. 

The  required  radiograph  is  made  as  follows : 

Patient  standing  with  sternum  flat  against  upright  plate 
holder:  target-plate  distance,  6  feet;  target  level  opposite 


THORACIC  VISCERA 


413 


^ 

E 

^N 

\ 

y 

\ 

/ 

» 

\ 

1 

r 

\ 

1 

\ 

i 

( 

»               \ 

b 

\ 

<« 

\ 

K 

\ 

•a 

t 

fl    ©rrj 

o 

o3  -a  O) 

^  %o 

«H 

r3   O   O 

o 

.2   o   tn 
^   I-   fc- 

E  "  o 

,^ 

o3 

'^   s;  rt 

bcS'*-' 

03 
-4J 

ct:  ^- 

.    fl 

•  rH      '^      a* 

CO  a> 

<y  ~-  ^ 

O     DO 

fH        .-'       O 

+^        S 

rJ   Oj 

m 

«     ~ 

C     03 

P.     X            . 

O    c3 

Ty 
III 

tierit 

0;     « 

^-3 

^-  -^^  " 

PQ  +* 

c;  ^-  ^ 

GO    o 

.•  1 

T-i  P.-CJ 

r^    " 

<V)     o 

r-i     H 

rt  •«  > 

El 

-T^     r^    (-!"i    ^ 


O    '^     S3 


o 


<4-l     S 

s  ^ 


ci 


^  -^  & 
•-  2  ^ 

o  ^  ^  £ 

S  "-^  o 
■^   C  e 


S  ^ ^  ^-t 


?^    '^     C 


©  o 

C    C- 


^S 


>  o  o  S 


.^ 

4i 

(U 

rt 

^ 

M 

>.3 

T3 

T-l 

Xi 

? 

» 

Tl 

^ 

d 

0) 

Fi 

c3 

60 

T3 

rt 

<D 

a 

<i> 

<1> 

> 

> 

m 

bC 

a 

(Tl 

m 

»-i  -p 

o3 

a« 

.2   M 

dja 

O  O 


(-.■rt 
C3T3 

^.2 


Ti 

05 

C3 

a 

d 

■P 

o 

> 

c3 

0)  +s 

JS 

03 

rl 

OJ 

XJ 

O 

» 

m 

X3 

d 

611 

O 

QJ 

-i 

IS 

il> 

0) 

»- 

o 

^d 

a 

O-ki 

.d 

e3 

i) 

<Bja 

Xi 

a 

43 

2 

o 

d 

w  a 
0 

'S 
d 

■   ■   •   '■   •fijpl^<^(j^^s[ijsfe^fe^sliis(i<    "^fest^    "J^    'J^fc 

M 
O 
4) 

2 
>> 

o 
CO 

d 

-pl-H 

-d 

'|a 

•     •  CO  CO  CO  CO -<*<  10 '^  TjH  10  iC  10  iCiC  10  10  lO  CD  CD  «:>  «D     -CD     -  CO  I>  t^  t^  t^  t^     • 

d 
> 
"Si 

CO 

'•  ifkitLifiii^^i^^^fL^l^pL^^feSfegi^fxii^fx;  :^  :S(x;ii;:^fc;S  • 

03 

bO 

03 
O 

-P  d 

as 

•  lO  CD  t^  t^  00  05  05  0  0  r-i  I-H  <N  <N  CO  CO -^  ■*     'CDiCCDt^t^     •  05  CO  O  05  "-H  O     • 

•  iC  lO  »C  iC  lO  iC  lO  CO  CD  CD  CD  CD  CD  CD  CO  CD  CO     •  CD  CD  CD  CD  CD     •  CD  CD  t>  CO  t>  t^     • 

■0  (M  lO  10  t-O  OC^  (N  iCiON't^OO  COCO     •  00  iC  00  O  O     •  CO  CO  CO  lO  O  00     • 

:pL;pL;^CL;^fx;^f^^PL;^PL;^fL;^fe^  '^^^^^  ^fLi^fL;^^^  : 

a 
0 

d 
0 

iCCOOOOcO-*(MOOOcO'*iNOOOcDiOCO(NOOOt^>CCO(N'-H0500COiC'*COC<l 

t^oocjioiO'-iiMcoco-^iocot^t^oooio^iMc^coTtHiocoh-t^ooaio^ojco 

■*-*Tt<T}<iOiCiOiCiCiCiO'CiCiOiOiOcOCOcOCOcOcOcOcOCOcOCOCDI>t^t^t^ 

-d  t:+i 

•s » a 

a 
0 

t^^iOOiCOt^'-ii005COt^<NcDO'*05COt^iMcOOiC05COOOiNt^i-HCO-^iOO 
■»tiiOiOiOcOCDt--t^t^000005050'-iOT-i,-iea(NCOCOCO-^rfiiOiCCDCDt^t^OO 
(N<NC^iM(M(NiMC<)(MC<l<MC^<MC0C0C0C0COC0COC0C0COC0COC0C0COC0COCOC0 

+3 

»  o  o 

bi 

050(M'*i01>050<N-<*<iOt>050iMTt<iC1^050iM-*COOOO'-ICOiOt^050C^ 
05OOOOOO'-i^'-iT-HrH,-iiMC<|(NC<l(NC<)C0C0C0C0C0Tj<Tj(T}*-<J(Tj4Tl<i0iC 

iOiOcOt^0000050'-i,-iO^COTt<rt<iOCDt^0000050'-H^iMCOTt4iOu:)COt^OOC5 
•^■^■<i<-^'*-<*-<tiiOiCiO>OiOiOiCiO»OiOiO»CliOcOCDcOcOcOCDCDCDCOcOCOCD 

ag.2 

a 
0 

•TjiiO     -COt^     -00     -Ol             '-' <N     -co     • -^     -lO     -co     -t^OO     -OS     •           •'-1     • 
'.^^     .^Ht-H     .,-H     .,H,-iiM05iM     -iM     -(M     -iM      -(N     -(MM     -(N     -CO     -CO     • 

"S  «  ca 

03    H   0) 

01  5  t 
K-d*< 

CO 

a 
0 

cr 
m 

C0Tt<iCC0t^00aiO^0qc0-*>OCDt^Q005Or-i(NC0Tj<i0CDt^000>O'-H(NC0'* 
0>050505030505OOOOOOOOOO^'-i^'-i^^i-irH^i-i(N(N(NiN(M 

o 

»o 

t^r^r^x 

•XC5 

■oo 

•'-i'-i(N(N 

•    •coco 

.-J<       . 

•lO 

.       .C>       • 

.    . 

. 

. 

.    .    . 

—  -^  o  o 

•  oo 

■t>r^ 

•t>t^t>.t~- 

•    •I>t^ 

•t^       • 

•t^ 

.       -t^       . 

CO-nrc 

■■*iC 

•XX 

•OOCOCO 

.       ■  LO  lO 

•X     • 

.^ 

•    •CO    • 

.    . 

t^t^t^t^ 

•  t^r^ 

■t^r^ 

•  X  X  X  X 

•     xx 

•X     • 

■  Cj 

•  o 

"""" 

■" 

P^^fsi-^; 

fe<5 

fa^. 

■  '^•^'^f^ 

<.-<, 

■  <<,    ■ 

•  «< 

■    ■«-',     • 

OCl-^O 

■c^i  -^ 

•     -(N 

•CO    •    --f 

■■■o    • 

t^  -^t^t^ 

•t^i> 

•    -r^ 

■  t^    •    •t- 

■    •t^t^ 

■t^    • 

DClCO  30 

.L~0 

•     •CO 

• lO     •     •  X 

•    •oo 

•CO      • 

,    . 

r^t>xr^ 

■X  X 

•    -x 

•X    •    •x 

•    •doi 

•05      • 

f-H  f-H  1— I  I— t 

■" 

•     ■ .— 1 

■^  •  --^ 

IJl,  ^^  ^ 

■~  '^ 

•    •< 

•<>;    •    •^^ 

•  •^-^ 

•<    • 

M  — 1        •  M 

.-t*    . 

•  LO        •  O       • 

. 

t^t^      r^ 

•      r^ 

■  t>    . 

•t^    -t^    • 

coo    -fO 

.     .lO 

•X     • 

•  -^    'CO    • 

. 

XX    -x 

•    -x 

•X     • 

•  C5      ■  Ci 

--  — 1         ■  rH 

•  >— ( 

•  »— 1 

• .— t     ■  ^^ 

^§  :^ 

:  -i 

■i,  ■ 

:^  -i  ■ 

>--  o  r;  X  t^  •"  L'^ 

10^  OC  C: 

xr^i> — 

■d-OTfTfT}<Ti<Tl'-#Tf'* 

C0C0C0C0'*-*-*-rt<'*'*'#LO 

r^  X  c;  o  -^  oa 

CO  ■*  LO  -^  -^ 

t^x  c:;o 

-^oqco 

Tf 

uO  O 

t^x  oo 

1— *  oi  CO  ^  LO 

o  t^  X  o  o  rH-eq 

COtIhlO 

or^ 

t^t>t^t^t^l>t^XXXXXXXXXXXC3C5C5C3 

o; 

oo 

w     w     w     w 

'-"-' 

^ 

'"' 

^1-,^ 

rHi-l 

'-' 

1-1 1-1 

-I-  C:  -+  X 

CO  X  CO 

t^  C^l  t-- 

^   O   tM   -^  ,-1 

lO  OlO 

^l>Mt^ 

oi  xco 

XCO 

o 

-f  o 

X  X  c;  cr. 

-H   M   C^] 

CO  CO  rt<  ■*  LO 

L-  -j:  -^  ^  t-  X  X 

."^ 

c^  o 

Oi-^c^c^cocoTt<^ 

LO  LO 

•^ 

■^y 

r-t^  X  X  o 

wi 

•^  1— ( 

't^-*'*^^'*^^'*^}-^'*-^'*-*^'*.-* 

LO  LO  LO  LO 

lO  LO  lO  lO  L. 

LO  LO 

LJ 

LO  LO 

l: 

-fwXO^^^0l^^^C5^ 

CO  LO  t^  C3  tH 

coi01>c: 

^  CO  lO  t^  o  -^ 

COLO  t^o 

^  CO  lO  t^  o 

-J  -v 

LO 

t> 

OOl-f 

ox 

^ 

05 -# 

UT  U?  Lt  O 

-^O:0OcCt>t^t-t^t>XXXXXOOCiC5OOOCOO-H^j-.j-jr^C^C^7^7jC0C0C0C0C^ 

m  lo  LQ 

iC  iC  iC  lO 

lO  LO  lO  LO  lO 

lO  lO  lO  lO  »0  LO  LO 

O^T-HC^^OTfL-^O-^t^XCiO— KNCOCOtJ^uO 

--0t^XC5O^lNC0C0'*L0t0t>XC: 

o^ 

M 

-.-1 

'tLO  -^ 

I>X 

o^ 

t^t>i>i>i>t^t>i>i>t^i>t>xxxxxxxxxxxoc; 

ooooooooooo 

— ^ 

>-^ 

— '  ^'  >^ 

s_'     -.^ 

y—i  1—1 

c^ro    -tH 

.  LO)  o  CO    •  i> 

•X    •o    • 

•  1—1     • 

05      •     • 

CO 

•TjH 

■LO       -O 

•I>    -x 

o    • 

•  ^   • 

oq    • 

CO    • 

CO  CO    'CO 

•coco 

■  I-H  T— 1 

CO    -co 
1— (    •  1—1 

•CO    •CO    • 
•  1—1     • .— 1     ■ 

1— 1     •  1-1     • 

1—1      • 

•* 

•TjH 

•  1—1     •  1— ( 

•   1—1           •   T-l 

^    • 

LO 

•LO        • 

•  I-l     • 

lO 

LO        • 

LO  O  I>  X  C5  O  -H 

(MC0-*i-0:0t^XCiO'-i(MC0Tj<i-0Ot^XOO'HCqC0 

Tf  LO  o  r-  X  o  o 

I-l 

C<ICOt)<l0  01>XOO 

e^c^c^c<i(Ncocococococococococo 

•^  •^  •*•*-*■*■*■*•*■*  LO  LO  LO  LO 

LO  lO  lO  lO  lO  lO  w 

^^ 

w 

vD  w!  w 

— 

T-l— '^— < 

»-'  1— l-H 

1—1  1—1  1—1  I— ( 

rH  1—1  1-1 

1—1 

rH  i-( 

1—1 1—1 1-1 1—1 

I-l  1— 1 1— 1 1-1 1-l 

03 
B 


w 


o 


-p  a 


iOiC':DCDt^C00503dOO'-i(N(MCOTtHOOt^G0020'-i(MCC-<i<'OcOt>0 
OOa50'-iiMCO'*iOcDOOC30'-<(NCC-^>OCOt^0005'-i(MfOTt<iOOI>0002 

T--(i-H(Nc^cqo.ic^(NC^c<ic^cococococococorococoTt<T}<-*-*TtiTt(TfT}<Tf< 


rfl    t:    -k^ 


o 


<T3 


w 


lO  O  CD  i-H  t^  (N  00  CO  00 -^  CT)  lO  1-  «3  (N  t^  CO  00  Tt<0  CD  (NN-fOOO -^  03  LO  O  O 
T-H(M(MC0C0T}HTjHi0i0CDcDI>0t.i'X)a50iOO'-<(M(NC0C0-^'*>OiCC0l^t^ 
CDCDCDCDcDCDCDCDcOCDCDOCDcDCDCDt^t^t^-t^t^t^-t^tvtvt^t^t^t^t-- 


c000OC0iOt^OiMTti;D00'-<C0iOt^Oi(M-^O00OC0i0t^05'-iTt<tD00O 
•^Tt<iO'OiOiOcDCDCDcDcDt^t^t^t^l>GOOOCOOOCl030C2CJOOOO'— I 

(^^o^c^^(^^(NC<^o^(^^(^^c-^(^^(^^(^^(^^(^^(^^(N(^^(^ll^^l^lC<^(^^(^^(^^cococococo 


c<^co^lO:ot^ooo30^(^^co^lOcD^^G0050'-le<l^OTt^lOco^>ooo50'-| 

.-i.-i^r-i,-i,-i,-i^(MC<l(NC<l(M(M(N(N(M(MC0C0C0COCOCOCOC0COCOTt<Tti 


•Th 

•lO 

•CD 

•t^ 

•00 

•a> 

■  i-t 

•iM 

•CO     • 

•Ti<       . 

•lO     • 

.(^          . 

■iO 

■  lO 

•>C 

•iCi 

■   7—1 

•lO 

■lO 

•CD 
•  1—1 

■CD 
•  i-< 

•CD 

•  o    . 

•  tH       • 

-CD     • 

•CD     ■ 

•!-(,• 

■  CD     • 

•    T— 1            • 

K 


THORACIC  VISCERA 


417 


spine  of  the  ninth  thoracic  vertebra ;  patient  to  hold  breath 
after  a  moderately  deep  inspiration.  A  good  intensifying 
screen  should  be  used.  It  is  advisable  to  give  the  patient 
a  glass  of  water  to  drink  immediately  before  making  the 
exposure  and  have  him  swallow  air  with  the  water.  The  re- 
sulting air  bubble  in  the  stomach  aids  in  outlining  the  apex 
of  the  heart. 


Fig.  190.     Planimeter. 

After  the  radiograph  is  dry  it  is  best  to  accentuate  the 
outline  on  the  plate  by  india  ink  or  a  soft  black  pencil, 
and  the  unregistered  outline  must  be  filled  in  as  shown  in 
Fig.  188.  Then  a  tracing  is  made  on  paper  (Fig.  189)  and 
the  area  is  determined  either  by  a  planimeter^  (Fig.  190), 
or  by  ruling  parallel  lines  one  centimeter  apart  in  two  di- 
rections at  right  angles  and  counting  squares,  estimating 
fractions.  The  lines  MR,  ML,  Figs.  188  and  189,  and  the 
diameter  of  the  aortic  arch  and  a  point  indicating  the 
median  line  of  the  body  should  be  indicated  on  the  tracing. 
The  record  furnished  should  include:  (a)  weight  of  pa- 
tient stripped,  (b)  age,  (c)  height  without  shoes,  (d)  trans- 

^  Instructions  for  the  use  of  a  planimeter  are  furnished  Trith  the 
instrument  by  the  maker  and  these  instructions  should  be  carefully 
observed.  The  user  will  find  it  advisable  to  check  his  work  by  laying 
out  a  rectangular  diagram  of  known  area  and  testing  the  accuracy 
of  his  reading  by  measuring  the  same. 


418  U.  S.  AR]\1Y  X-RAY  MANUAL 

verse  diameter  MR  +  ML,  (e)  aortic  diameter,  (f)  heart 
area  from  tracing. 

In  using  this  method  it  is  assumed  that  the  increase  in 
area  of  heart  shadow  on  the  plate  due  to  the  fact  that 
the  rays  are  not  parallel  is  equivalent  to  the  usual  increase 
in  shadow  area  for  the  sitting  position  over  that  for  the 
standing  position. 

From  the  tables  read:  the  normal  heart  area  shadow, 
diameter  and  volume  (1)  for  a  person  of  the  same  height, 
(2)  for  one  of  the  same  weight  as  the  patient.  The  area 
(f)  should  fall  between  the  normal  for  like  height  and  that 
for  like  weight.  If  the  area  (f )  is  less  than  the  smaller,  or 
exceeds  the  greater  of  those  taken  from  the  table  the  heart 
may  be  regarded  as  of  abnormal  size. 

In  such  cases  compute  the  per  cent  variation  of  (f) 
from  the  nearer  of  the  two  from  the  table  and  enter  on  the 
record.  If  this  exceeds  10  per  cent  and  symptoms  are  pres- 
ent, there  is  a  fair  probability  of  pathology. 


URINARY   TRACT 

It  is  not  necessary  at  the  present  clay  to  discuss  the 
obvious  value  and  importance  of  the  x-ray  examination  of 
the  urinary  tract.  It  is  sufficient  to  state  that  it  is  the 
best  and  only  single  method  of  demonstrating  the  pres- 
ence of  a  calculus;  that  furthermore  it  also  discloses  its 
location,  its  size,  and  its  shape,  and  tells  the  number,  if 
more  than  one  are  present.  For  this  reason  it  is  a  very 
valuable  aid  in  the  decision  whether  operative  procedure  is 
necessary  or  an  expectant  course  is  permissible.  In  the 
latter  eventuality  it  is  the  only  means  at  our  disposal  which 
tells  us  whether  the  calculus  is  passing  downward  or  re- 
mains stationary,  whether  it  increases  in  size,  and  whether 
there  is  a  tendency  for  the  formation  of  additional  calculi. 

Preparation  of  the  Patient. — To  obtain  satisfactory  re- 
sults it  is  necessary  to  eliminate  confusing  shadows  of  sub- 
stances found  in  the  gastro-intestinal  tract  and  to  get  rid 
of  accumulations  of  gas  in  the  colon  which  tend  to  obscure 
the  kidney  shadows  and  may  obliterate  small  calculi.  For 
that  reason  it  is  a  condition  precedent  to  every  examina- 
tion of  the  urinary  tract  to  prepare  the  patient  by  thor- 
ough catharsis.  Castor  oil,  about  lMi-2  ounces  for  an 
adult,  is  the  best  cathartic  for  this  purpose,  as  it  helps  to 
eliminate  gas.  If,  for  a  good  and  sufficient  reason,  it  can- 
not be  used,  a  large  dose  of  one  of  the  other  vegetable  ca- 
thartics may  be  given.  The  metallic  substances,  in  particu- 
lar calomel,  should  never  be  used,  because  they  have  a 
tendency  to  produce  gas. 

419 


420  U.  S.  ARMY  X-RAY  MANUAL 

The  cathartic  should  be  administered  the  evening  before 
the  examination,  the  patient  abstaining  from  all  food  in  the 
interval.  For  that  reason  it  is  best  to  make  these  examina- 
tions in  the  morning,  omitting  breakfast,  but  allowing  the 
patient  to  take  a  little  coffee  or  tea.  If  the  examination  is 
made  later  in  the  day  the  patient  might  have  to  starve  too 
long. 

An  enema,  if  properly  administered,  would  be  of  assist- 
ance. Experience,  however,  teaches  that  it  is  very  diffi- 
cult to  have  it  done  properly,  and  for  that  reason  it 
should  be  avoided  as  a  routine  measure.  In  those  cases, 
however,  where  the  administration  of  catharsis  is  contra- 
indicated  or  time  does  not  permit  it,  a  low  S.  S.  enema  may 
be  given  an  hour  before  the  examination,  the  tube  being 
retained  in  the  rectum  for  half  an  hour  to  facilitate  the 
escape  of  gas. 

If  it  can  be  avoided,  the  patient  should  not  be  examined 
during  or  immediately  following  an  attack  of  colic.  During 
an  attack  he  is  usually  too  sick  for  such  an  examination. 
Besides,  at  that  time  and  immediately  after,  he  is  invari- 
ably under  the  influence  of  an  opiate  or  similar  drug  which 
interferes  with  efficient  catharsis  and  almost  always  causes 
the  accumulation  of  gas  in  the  colon. 

Technique. — Several  observers,  notably  Shenton  and 
Manges,  have  advocated  fluoroscopy  in  the  examination  of 
the  urinary  tract.  While  in  the  hands  of  careful  and  ex- 
ceptionally skillful  operators  this  method  is  of  value,  yet 
in  the  hands  of  the  average  operator  radiography  yields 
the  best  results.  Therefore  this  article  is  based  entirely 
upon  the  radiographic  method. 

The  most  common  method  employed  in  the  examination 
of  the  urinary  tract  is  the  one  in  which  the  patient  is  in 
the  recumbent  position,  the  tube  placed  above,  the  plate  be- 
low.   Most  roentgenologists  use,  in  addition  to  the  plain 


URINARY  TRACT 


421 


diaphragm,  the  compression  cylinder  or  cone.  Some  opera- 
tors, however,  use  merely  the  diaphragm,  and  others,  nota- 
bly Caldwell,  place  the  patient  in  the  prone  position,  the 
tube  below  the  table  and  the  plate  above  the  patient  at  the 
back,  Fig.  191.  Placing  a  rubber  bag  filled  with  air  under 
the  patient,  his  weight  will  produce  the  necessary  compres- 
sion in  this  position.    Inasmuch  as  the  base  hospital  tables 


Fig.  191.  Patient  prone;  tube  below  table;  plate  held  against 
patient's  back  by  screen  holder.  This  illustration  shows  examination 
for  upper  half.  Tube  and  plate  would  have  to  be  moved  downward  to 
bladder  region  for  lower  half. 


used  in  the  army  are  arranged  for  work  with  the  tube 
above,  the  technique  best  adapted  for  these  tables  will  be 
described  here.  There  are  many  variations  in  the  technique 
employed.  When  a  small  cylinder  or  cone  is  used  it  is  nec- 
essary to  make  five  exposures  to  cover  the  urinan-  tract, 
namely,  one  for  each  kidney,  and  the  upper  third  of  each 
ureter,  one  for  the  middle  portion  of  each  ureter,  and  the 
fifth  for  the  lower  third  of  both  ureters  and  for  the  blad- 
der.   Others,  by  using  a  slightly  larger  cylinder,  make  only 


422 


U.  S.  ARMY  X-RAY  MANUAL 


four  exposures,  including  the  middle  third  of  both  ureters, 
on  one  plate.  The  writer  prefers  to  use  a  cylinder,  8^^ 
inches  in  diameter,  which  enables  him  in  the  majority  of 
cases  to  make  one  exposure  (or  set  of  stereoscopic  expos- 
ures) for  the  upper  half,  Fig.  192,  and  another  for  the  lower 
half.  Fig.  193,  of  the  urinary  tract.  This  technique  is  some- 
times modified  to  suit  individual  cases.     If  the  patient  is 


Fig.  192.  Position  for  upper  half  of  urinary  tract;  showing  com- 
pression sponge,  knee  support  and  insulating  sheet  protecting  patient's 
knees  against  spark  from  terminal  of  tube. 


very  stout,  it  is  necessary  to  make  special  exposures  over 
individual  kidney  regions.  Similarly,  special  exposures  are 
made  over  regions  which  are  particularly  under  suspicion 
or  for  which  a  confirmatory  examination  is  desired. 

In  older  men  and  in  all  cases  where  concretions  in  the 
prostate  are  suspected,  an  examination  of  the  bladder  region 
should  be  made  in  the  dorsoventral  position.  In  this  ex- 
posure the  tube  should  be  tilted  slightly  upwards  and  cen- 


URINARY  TRACT 


423 


tered  as  nearly  as  possible  on  the  sacrococcygeal  junction, 
Fig.  194. 

In  all  cases  the  entire  urinary  tract  should  be  examined 
no  matter  whether  the  symptoms  point  to  a  definite  region 
or  not.     Only  by  observing  this  rule  will  mistakes  in  diag- 


FiG.  193.     Position  for  lower  half  of  urinary  tract. 


nosis  be  avoided.  For,  in  a  great  number  of  instances  the 
calculus  may  be  found  on  the  side  opposite  to  that  indi- 
cated by  the  symptoms.  An  examination  of  a  single  area 
is  permissible  only  when  it  is  done  for  verification. 

In  making  the  examination  with  the  cylinder,  it  is  ad- 
visable to  tilt  it  upwards  for  the  upper  half  and  down- 
wards for  the  lower  half.    The  operators  w^ho  are  examin- 


424 


U.  S.  ARMY  X-RAY  IMANUAL 


ing  individual  areas  with  the  smaller  cylinders  or  cone  as  a 
rule  try  to  get  the  upper  rim  of  the  cylinder  under  the  free 
border  of  the  ribs.  (The  term  upper  and  lower  are  mad^^ 
with  reference  to  the  patient,  the  upper  referring  to  ce- 
phalic, the  lower  to  caudal  end.)    The  advantage  obtained  by 


Fig.  194.     Position  for  bladder  and  prostate. 


getting  the  cylinder  or  cone  under  the  ribs  is  that  calcifi- 
cations in  the  costal  cartilages  are  not  projected  upon  the 
kidney  shadows,  and  thus  confusion  is  avoided. 

The  beginner  will  soon  learn  which  are  the  best  angles 
for  the  apparatus  he  is  using.  As  a  guide  he  should  use 
the  accompanying  illustrations  until  he  has  acquired  his 
technique. 


URINARY  TRACT  425 

Various  devices  are  employed  in  order  to  prevent  the 
abdominal  wall  from  protruding  into  the  opening  of  the 
cone.  One  of  these  is  the  attachment  of  an  aluminum  hemi- 
sphere to  the  lower  opening  of  the  cone.  Another  is  to  place 
between  the  cylinder  or  cone  and  the  patient's  abdomen  a 
rubber  bag  filled  with  air  or  a  pad  made  of  loofah  sponges, 
or  absorbent  cotton.  These  must  be  wider  than  the  rim 
of  the  cylinder  or  cone  and  of  ample  thickness.  They 
should  be  tested  by  radiography  or  fluoroscopy  to  ascertain 
that  they  are  free  from  shadow-casting  substances. 

Quality  of  Tube. — It  is  best  to  use  a  tube  of  fairly  low 
gap,  about  3  to  4  inches  (using  a  slightly  lower  gap  perhaps 
for  the  Coolidge  than  for  the  gas  tube)  at  40  ma.  or  more. 
The  length  of  exposure  depends  upon  the  speed  of  the 
plate  and  the  current  used.  It  may  vary  from  2  to  6  and  be 
as  long  as  10  and  15  seconds.  Great  rapidity  is  not  needed, 
if  the  parts  can  be  properly  immobilized  and  the  patient 
can  be  made  to  hold  his  breath  during  the  exposures  over 
the  upper  half  of  the  urinary  tract.  Complete  arrest  of 
respiration  holds  the  diaphragm  still  and  the  kidneys  at 
rest,  enabling  the  operator  to  obtain  good  kidney  outlines. 

Position. — It  is  very  important  to  have  the  spine 
straightened  out,  so  that  it  completely  touches  the  plate. 
In  those  instances  (and  they  are  many)  where  the  pa- 
tient's back  is  so  curved  that  the  simple  recumbent  position 
will  not  straighten  it  sufficiently,  his  shoulders  may  have  to 
be  raised  and  the  hips  and  knees  flexed.  When  doing  the 
latter,  one  must  be  careful  not  to  bring  the  tube  terminals 
too  near  the  knees.  If  that  cannot  be  prevented,  a  good 
heavy  insulator  ought  to  be  interposed,  and  if  that  is  not 
feasible,  one  had  better  allow  the  back  to  remain  curved 
(Fig.  195). 

Clothing  or  bandages  in  the  path  of  the  rays  between  the 
target  and  the  plate  should  be  avoided.    In  case  the  removal 


426 


U.  S.  AmiY  X-RAY  MANUAL 


of  bandages  is  not  permissible  correct  information  as  to 
what  is  hidden  by  tlieni  must  be  obtained  before  stating 
definitely  that  a  certain  shadow  is  a  calculus.  It  is  well  to 
remember  that  dried  blood  or  pus  in  a  bandage  or  dressing 
will  cast  a  shadow. 


Fig.  195.  General  view  of  table;  position  of  patient  on  table  and 
method  used  in  straightening  patient's  back;  relative  position  of 
table  and  tube  stand  on  side  opposite  to  screen  carrier. 


Quality  of  the  Plate. — The  greatest  difficulty  in  this  ex- 
amination is  encountered  when  no  calculus  is  seen  on  the 
plate.  The  question  then,  arises,  is  the  plate  good  enough 
to  make  a  negative  diagnosis  with  absolute  certainty.  Credit 
is  due  to  the  late  Charles  Lester  Leonard,  of  Philadelphia, 
for  having  laid  down  the  rules  which  with  but  one  addition 
hold  good  to-day.     These  rules  are :  a  plate  to  be  consid- 


URINARY  TRACT  427 

ered  as  havings  the  necessary  radiographic  quality  must 
show  at  least  the  11th  and  12th  ribs,  the  transverse  processes 
of  the  lumbar  vertebra^  and  the  edge  of  the  psoas  muscle. 
The  only  addition  to  Leonard's  rule  is  that  at  the  pres- 
ent day  one  must  also  demonstrate  the  kidneys.  In  the 
days  of  Leonard  the  x-ray  technique  had  not  been  de- 
veloped sufficiently  to  enable  us  to  obtain  kidney  shadows 
in  all  cases.  Even  to-day  it  is  sometimes  difficult  to  live 
up  to  this  rule.  The  right  kidney  is  frequently  obscured 
by  the  presence  of  gas  at  the  hepatic  flexure.  But  when  on 
a  plate  showing  both  sides  of  the  upper  half  of  the  urinary 
tract,  one  kidney  is  clearly  shown,  we  may  accept  the  plate 
as  of  good  quality,  though  it  does  not  show^  both  kidneys 
clearly.  Another  point  to  remember  is  that  great  contrast 
between  the  spine  and  pelvis  on  the  one  hand,  and  the  soft 
tissues  on  the  other,  is  not  desirable.  Such  a  plate  pre- 
supposes an  overexposure  with  a  tube  of  low  penetration  in 
which  a  small  calculus  may  have  been  obliterated. 

Pyelography. — In  the  vast  majority  of  cases,  the  simple 
x-ray  examination  of  the  urinary  tract  is  made  for  the 
determination  of  the  presence  or  absence  of  a  calculus. 
Other  conditions  of  the  tract  cannot  be  determined  readily 
or  at  all  by  such  an  examination.  It  is  then  necessary  to 
resort  to  additional  methods  in  such  cases. 

The  most  important  of  these  methods  is  pyelography,  i.  e., 
the  demonstration  of  the  renal  pelvis  and  calyces,  of  the 
ureter,  and  of  the  bladder,  by  the  injection  of  substances 
which  are  opaque  to  the  rays.  The  substance  most  com- 
monl}^  used  in  this  country  at  the  present  day  is  a  solu- 
tion of  thorium  nitrate  in  about  10-15  per  cent  strength. 
CoUargol,  argj^rol,  and  other  silver  compounds  which  ere 
originally  used  are  now  less  -  generally  employed.  Other 
substances,  especially  insoluble  ones,  such  as  bismuth  emul- 
sions,  should   never  be   used.     As  they  cannot   be   com- 


428  U.  S.  ARMY  X-RAY  MANUAL 

pletely  washed  out  they  may  form  a  good  nucleus  for  the 
formation  of  a  calculus.  Thorium  nitrate  is  the  least  harm- 
ful of  all  these  substances.  The  method  of  injection  is 
either  by  gravity,  allowing  the  solution  to  flow  in  slowly, 
or  by  hand  injection.  The  advocates  of  the  gravity  method 
maintain  that  only  by  using  it  are  the  deleterious  effects  of 
pyelography  avoided.  It  is  the  writer 's  opinion,  based  upon 
considerable  experience,  that  the  method  makes  little  differ- 
ence. In  the  hands  of  a  careful  urologist,  either  method  is 
good.  But  no  matter  how  careful  a  urologist,  neither 
method  is  free  from  danger.  Pyelography,  therefore, 
should  be  employed  only  when  all  other  means  have  failed. 
The  roentgenologist  should  never  attempt  the  injection  him- 
self.i 

The  principal  conditions  which  may  be  demonstrated  by 
pyelography  are  the  following: 

1.  Enlargement  of  the  renal  pelvis,  congenital  or  ac- 
quired, such  as  hydronephrosis  and  pyonephrosis. 

2.  Malformations  of  the  renal  pelvis,  most  commonly 
due  to  tumor  of  the  kidney. 

3.  Cystic  kidney. 

4.  Horseshoe  kidney. 

5.  Fused  kidney. 

6.  Identification  of  shadows  within  the  kidney  outline 
as  extrarenal  or  intrarenal. 

7.  Constriction  or  kink  in  the  ureter. 

8.  Diverticulum  in  the  ureter. 

9.  Hydro-ureter. 

10.  Redundant  ureter. 

11.  Double  ureter  and  pelvis. 

12.  Size  and  shape  of  bladder. 

Demonstration  of  Calculi. — Calculi  are  demonstrable  to 

^  Those  interested  in  this  subject  are  referred  to  Braasch 's  excel- 
lent monograph  on  pyleography,  published  by  Saunders  in  1915. 


URINARY  TRACT  429 

a  greater  or  lesser  extent  according  to  their  chemical 
composition.  The  oxalates  and  the  calcium  carbonates  give 
the  best  shadows;  the  phosphates  are  next  in  density;  the 
urates  may  be  shown  very  faintly  but  generally  not  at  all. 
Fortunately,  the  latter  are  infrequent  in  the  ureter  and 
quite  rare  in  the  kidney.  In  the  bladder,  where  they  oc- 
cur most  often,  cj^stoscopy  comes  to  our  aid  in  locating  them. 

By  far  the  greatest  number  of  calculi  are  found  in  the 
ureters.  The  smallest  number  are  found  in  the  bladder. 
Renal  calculi  are  second  in  frequency.  They  are  often 
seen  to  be  of  very  large  size,  sometimes  occupying  about 
two-thirds  or  more  of  the  kidney  and  all  of  its  pelvis.  They 
are  very  often  bilateral,  and  frequently  multiple  in  one 
kidney.  Occasionally  such  a  calculus  represents  a  com- 
plete cast  of  the  renal  pelvis  and  of  all  the  calyces.  A 
small  calculus  may  be  readily  overlooked,  especially  when 
its  shadow  coincides  with  that  of  the  rib  or  is  situated  just 
at  the  tip  of  the  rib.  The  small  calculi  are  frequently 
shown  faintly  because  of  the  comparative  density  of  the 
kidney  shadow.  For  that  reason  it  is  difficult  to  distin- 
guish them  from  the  rib  if  they  happen  to  be  projected 
upon  it.  Stereoscopic  examination  will  usually  help  in 
separating  the  shadows  of  the  calculus  and  of  the  rib. 
Where  stereoscopy  is  not  feasible,  a  change  in  the  angle 
of  projection  may  sometimes  throw  these  two  shadows  apart. 

Whenever  a  faint  shadow  is  seen  which  is  suggestive  of  a 
calculus,  especially  if  it  is  located  in  the  kidney  regions, 
a  confirmatory  examination  should  be  made  before  making 
the  diagnosis  absolute.  It  is  good  policy  in  almost  all  cases 
to  make  a  confirmatory  examination  before  operation. 

The  demonstration  of  vesical  calculi  is  generally  much 
more  difficult  and  less  satisfactory  than  that  of  other  cal- 
culi. The  reason  is,  first,  that  the  great  majority  of  them 
are  composed  of  pure  uric  acid  or  of  a  combination  of 


430  U.  S.  ARMY  X-RAY  ]\IANUAL 

urates;  secondly,  they  occur  largely  in  individuals  with 
prostatic  disease,  with  thickened  bladder  walls,  and  marked 
retention  of  urine,  all  of  which  add  to  the  dilBculty  in  dem- 
onstrating them  by  the  x-ray. 

Prostatic  concretions  are  readily  demonstrable,  but  are 
not  very  frequent. 

To  demonstrate  uric  acid  calculi  in  the  ureter,  pyelo- 
graphy, or  more  strictly  speaking,  ureterography,  may  have 
to  be  employed.  The  opaque  solution  will  cover  the  trans- 
parent calculus  for  the  time  being,  or  will  ascend  to  that 
area  and  show  a  dilatation  of  the  ureter  at  that  point,  thus 
demonstrating  the  calculus.  Fortunately,  the  percentage 
of  such  calculi  is  small. 

Sources  of  Error  in  Diagnosis. — Not  every  concretion 
or  shadow  seen  on  x-ray  plates  of  the  urinary  tract  is  a 
urinary  calculus.  While  it  requires  a  great  deal  of  experi- 
ence to  differentiate  between  them  readily,  it  is  still  pos- 
sible to  give  the  beginner  a  fair  idea  how  to  avoid  errors  in 
diagnosis. 

In  the  kidney  regions,  for  example,  small  shadows,  some- 
times rather  indefinite,  are  freqeuntly  seen.  Careful  scru- 
tiny of  the  plate  may  indicate  that  the  direction  of  the 
calcification  is  in  line  with  the  costal  cartilages.  The 
difficulty  here  is  not  so  pronounced  when  these  concretions 
are  in  the  cartilages  of  the  free  border.  It  is  greater  when 
there  is  a  short  12th  rib,  the  tip  of  which  is  seen  within 
the  kidney  outline,  and  whose  cartilage  shows  partial  cal- 
cification, so  that  the  latter  appears  to  be  separate  and  dis- 
tinct from  the  rib  itself.  Occasionally  intestinal  contents 
at  the  hepatic  or  splenic  flexures  may  cause  considerable 
difficulty  in  the  interpretation.  Calcified  mesenteric  glands 
are  another  source  of  difficulty.  In  the  lower  part  of 
the  urinary  tract,  especially  near  the  bladder,  there  are 


URINARY  TRACT  431 

seen,  with  very  g-reat  frequency,  a  number  of  small  con- 
cretions whose  shadows  are  very  dense  and  circular  in  out- 
line and  quite  distinct  in  contour,  which  are  not  calculi. 
For  want  of  a  better  name  they  have  been  called  phle- 
boliths. 

The  following  is  a  partial  list  of  shadow-producing  sub- 
stances reported  by  various  authors  which  have  given  rise 
to  confusion  in  diagnosis.  It  necessarily  cannot  be  com- 
plete. 

1.  Fruit  pits. 

2.  Fecaliths;  the  most  confusing  of  these  is  a  concre- 
tion in  the  appendix,  because  of  its  shape  and  position  and 
also  because  it  frequently  gives  rise  to  symptoms  resem- 
bling those  of  urinary  calculus.  Microscopic  blood  has  even 
been  found  in  such  cases. 

3.  Residues  of  metallic  medication  such  as  bismuth, 
barium,  Blaucl's  pills,  etc. 

4.  Foreign  bodies  in  the  intestinal  tract,  including  Mur- 
phy's buttons.  The  latter,  however,  can  be  more  readily 
recognized  by  their  characteristic  shape  and  also  from  the 
history. 

5.  Gall-stones ;  a  differential  point  for  these  is  that  they 
are  usually  about  the  size  of  a  cherry  pit,  distinctly  out- 
lined, either  sharply  circular  or  facetted,  and  are  more 
transparent  in  the  center  than  at  their  margin. 

6.  Calcified  mesenteric  glands;  these  can  be  recognized 
to  some  extent  by  their  appearance.  They  are  usually 
not  as  compact  and  dense  as  urinary  calculi  but  are  reticu- 
lated. They  are  as  a  rule  quite  mobile,  so  that  they  will 
change  their  position  with  regard  to  the  kidney  to  a  greater 
extent  than  can  be  accounted  for  by  even  the  grossest  dis- 
tortion in  position, 

7.  Calcifications  in  tuberculous  kidneys  and  inspissated 


432  U.  S.  AR]\IY  X-RAY  MANUAL 

pus.    These,  though  strictly  speaking,  not  calculi,  may  for 
practical  purposes  be  considered  such. 

8.  Calcified  blood  clot  in  a  carcinomatous  kidney.  Ab- 
scess of  kidney  with  scar  tissue  in  the  kidney. 

9.  Carcinoma  in  the  head  of  the  pancreas. 

10.  Calcifications  at  the  bifurcation  of  the  aorta. 

11.  Calcification  of  the  tips  of  the  transverse  processes 
of  the  lumbar  vertebrae,  or  artefacts  in  this  region  pro- 
duced by  the  crossing  of  the  border  of  the  psoas  muscle 
just  inside  the  tip. 

12.  Calcifications  in  the  body  portions  of  the  pelvis, 
especially  in  the  ilium,  the  so-called  compact  islands,  and 
small  exostoses  of  the  ilium  or  of  the  ischial  spine. 

13.  Calcifications  of  portions  of  the  ureter. 

14.  Sclerosis  of  the  iliac  arteries. 

15.  Calcifications  of  the  vasa  deferentia. 

16.  Calcified  myoma  or  dermoid  cyst. 

A  thorough  inspection  of  the  body  surface  of  the  pa- 
tient at  the  time  of  the  examination  will  aid  in  avoiding 
confusion  in  the  following  instances : 

17.  Warts  and  pigmented  moles,  especially  when  in  good 
approximation  to  the  plates. 

18.  Scars  of  former  operations. 

19.  Adhesive  plaster,  especially  when  tied  in  a  knot  or 
folded. 

Shadows  due  to  intestinal  contents  are  usually  absent 
at  a  reexamination  after  more  thorough  catharsis.  If 
shadows  persist  after  repeated  catharsis  and  their  nature 
is  still  doubtful,  it  will  be  necessary  to  reexamine  the  patient 
with  an  opaque  catheter  in  the  suspected  ureter,  prefer- 
ably  stereoscopically,   before    one    can   tell   whether   this 


URINARY  TRACT  433 

shadow  is  due  to  a  concretion  in  the  urinary  tract  or  out- 
side of  it. 

In  one  instance  mentioned  above,  namely,  calcifications 
of  portions  of  the  ureter,  even  the  opaque  catheter  may 
not  help  to  clear  up  the  condition,  because  it  will  usually 
be  arrested  at  the  area  of  calcification  and  in  this  way 
apparently  confirm  the  presence  of  a  calculus.  For  prac- 
tical purposes  this  makes  no  difference,  inasmuch  as  surgi- 
cal removal  of  the  calcified  portion  of  the  ureter  is  neces- 
sary to  relieve  the  patient  of  his  symptoms. 

Use  of  the  Opaque  Catheter. — In  all  doubtful  cases 
where  shadows  are  seen  within  or  near  the  course  of  the 
ureter,  the  diagnosis  can  be  rendered  more  certain  by  a 
reexamination  with  an  opaque  catheter  in  the  suspected 
ureter.  Though  the  ureter  follows  a  fairly  regular  course, 
there  frequently  are  deviations  from  the  normal,  which 
seem  to  place  a  shadow  outside  of  the  ureter.  The  opaque 
catheter,  especially  when  aided  by  the  stereoscope  will  as- 
sist in  making  the  diagnosis. 


GASTRO-INTESTINAL   TRACT 

In  the  x-ray  examination  of  the  gastro-intestinal  tract 
we  must  remember  that  we  are  not  dealing  with  fixed  or- 
gans, but  with  those  that  vary  greatly  in  size,  shape,  posi- 
tion and  motility  according  to  conditions.  It  is  therefore 
difficult  to  differentiate  between  supposedly  abnormal  in- 
dications, either  congenital  or  temporary,  and  those  that 
are  pathological.  The  most  definite  of  the  latter  are  as 
follows : 

1.  Interference  with  function. 

2.  Irregularities  in  outline,  such  as, 

Filling  defects. 

Projections, 

Niches, 

Diverticula, 

Hourglass  deformities. 

Spasms. 

3.  Extreme  changes  in  position. 

Technique. — Since  the  gastro-intestinal  tract  is  not  di- 
rectly demonstrable  by  the  x-ray,  it  is  necessary  to  intro- 
duce some  opaque  substance  which  should  not  interfere  with 
function  and  must  be  harmless. 

''Barium  Sulphate  for  X-Eay  Diagnosis"  is  the  agent 
most  commonly  employed.  While  the  constituents  of  the 
barium  meal  vary  with  many  operators,  it  is  well  to  empha- 
size that,  whatever  meal  is  used,  it  should  be  adhered  to  in 
all  examinations,  as  different  meals  may  cause  marked  dif- 
ferences in  function,  especially  of  the  stomach. 

434 


GASTRO-IXTESTIXAL  TRACT  435 

In  studj^ing  the  lesions  of  the  esophagus,  a  thick  paste 
made  of  barium  sulphate  and  mucilage  of  acacia  should  be 
employed.  A  barium  water  mixture  should  be  used  first, 
as  a  very  narrow  stricture  may  be  present.  For  the  study 
of  the  stomach,  4  oz.  of  barium  sulphate  mixed  with  12 
oz.  of  buttermilk,  or  one  of  the  fermented  milks,  is  the 
favorite  among  American  roentgenologists.  If  these  can- 
not be  obtained,  an  emulsion  of  mucilage  of  acacia  and 
barium  sulphate  with  water  can  be  readily  substituted. 

The  opaque  enema  is  composed  of  8  oz.  of  barium  sul- 
phate and  32  oz.  of  water  with  sufficient  mucilage  of  acacia 
to  make  an  emulsion.  Other  vehicles,  such  as  buttermilk 
or  a  mixture  of  equal  parts  of  condensed  milk  and  water, 
may  be  used.  Barium  or  bismuth  or  any  other  of  these 
opaque  substances  when  mixed  with  water  alone  sediments 
out  too  quickly  and  should  therefore  not  be  used  except  as 
above  noted. 

Preparation  of  the  Patient. — For  the  examination  of 
the  esophagus  and  the  stomach  by  an  ingested  meal,  the 
patient  should  present  himself  with  an  empty  stomach  but 
without  previous  catharsis,  ^"hen  the  opaque  enema  is  to 
be  used  the  colon  is  prepared  by  the  administration  of 
several  cleansing  enemata,  the  last  of  these  at  least  two 
hours  before  examination.  All  drugs  which  have  a  stimu- 
lating or  inhibitory  effect  upon  the  digestive  tract  should 
be  withdrawn  at  least  twenty-four  hours  before  the  ex- 
amination. With  the  barium  meal  as  described  above  the 
stomach  empties  normally  in  about  four  hours.  But  if  the 
barium  is  retained  up  to  six  hours  it  is  still  considered 
within  normal  limits.  A  retention  after  six  hours  of  about 
one-eighth  or  more  of  the  ingested  quantity  is  distinctly 
pathological.  On  the  other  hand,  perfectly  normal  stom- 
achs have  been  seen  to  empty  in  about  two  hours.  In  these 
cases,  however,  one  should  remember  that  achylia  gastrica 


436 


U.  S.  ARMY  X-RAY  MANUAL 


is  characterized  by  very  rapid  empt.yinf^  time.  The  small 
intestines  should  be  empty  six  hours  after  the  stomach  is 
clear.    The  cecum  begins  to  fill  about  four  hours  after  the 


Fig.  196.     Diverticulum  arising  from  posterior  wall  of  esophagus. 


meal ;  the  head  of  the  barium  column  is  at  the  hepatic  flex- 
ure at  six  hours  after  the  meal,  in  the  midportion  of  the 
transverse  colon  at  eight  hours  and  in  the  lower  portion  of 
the  descending  colon  at  twelve  hours.    Part  should  be  dis- 


GASTRO-INTESTINAL  TRACT 


437 


Fig.  197.     Benign  stricture  of  esophagus. 


charged  about  twenty-four  hours  after  the  meal  and  a  com- 
plete evacuation  ought  to  be  accomplished  in  forty-eight 
hours. 

Method  of  Examination. — In  making  an  examination,  a 
combination  of  the  fluoroscopic  and  radiographic  meth- 


438  U.  S.  ARMY  X-RAY  MANUAL 

ods  should  be  employed.  Both  methods  give  information 
as  to  size,  position,  shape  and  contour.  Plates  give  full 
detail,  especially  in  contour,  and  form  a  permanent  rec- 
ord. The  screen  has  the  great  advantage  of  permitting 
the  observer  to  study  the  tract  in  motion  and  to  palpate 
individual  organs.     It  is  therefore  indispensable. 

The  Esoph^-gus. — This  should  be  examined  for  the  fol- 
lowing lesions:  Diverticula,  benign  strictures,  malignant 
growths  and  spasms. 

Diverticulum  is  usually  found  just  below  the  jugular 
notch.  Since  it  may  lie  anteriorly,  posteriorly  or  laterally 
it  should  be  viewed  from  various  angles.  It  manifests  it- 
self by  a  shadow  outside  that  of  the  esophagus  and  is  gen- 
erally pouchlike  in  appearance  and  persists  after  the 
esophagus  is  empty.  Fig.  196. 

Benign  strictures  and  malignant  growths  are  similar  in 
appearance;  in  both  there  is  a  constriction  at  the  seat  of 
the  lesion  which  is  usually  conical  in  shape,  the  apex  point- 
ing downward,  accompanied  by  a  varying  degree  of  obstruc- 
tion. An  etiological  diagnosis  between  these  two  conditions 
cannot  always  be  made  but  when  the  edges  of  the  stricture 
are  serrated  it  is  more  likely  to  be  malignant.  Fig.  197  and 
Fig.  198.  In  malignancy  little  dilatation,  if  any,  is  ob- 
served, and  it  is  usually  found  at  the  level  of  the  bifurca- 
tion of  the  trachea  and  in  the  cardiac  end.  When  the  lat- 
ter obtains,  the  adjacent  part  of  the  stomach  is  frequently 
involved.  Benign  strictures  may  be  found  in  any  portion 
of  the  esophagus.  Age  will  frequently  aid  in  the  deter- 
mination of  the  condition. 

Spasm  is  intermittent  in  character,  may  occur  in  any 
part  and  is  usually  transitory.  The  most  common  form  is 
cardiospasm.  It  is  more  or  less  persistent  and  results  in 
a  dilatation  of  the  entire  esophagus  to  a  degree  not  seen 
in  any  other  conditions,  Fig.  199, 


GASTRO-INTESTINAL  TRACT  439 


^>;- 


J^ 


Fig.  198.     Carcinoma    of    esophagus    at    level    of    bifurcation    of 
trachea. 


440  U.  S.  ARMY  X-RAY  MANUAL 


Fig.  199.     Cardiospasm;   note  marked  dilatation  of  esophagus. 


GASTRO-INTESTINAL  TRACT 


441 


Stomach. — The  size,  position  and  shape  of  the  stomach 
depend  upon  the  habitus  of  the  individual 


Fig.  200.     Penetrating    ulcer     on    lesser    curvature     of    stomach. 
Spastic  hourglass  contraction  opposite  on  greater  curvature. 


Roughly  speaking,  the  high  transverse  stomach  ie  found 
in  fat  people,  the  cow-horn  type  in  the  medium  weight  in- 
dividuals, the  fish-hook  type  more  frequently  in  thin  indi- 


442 


U.  S.  ARMY  X-RAY  MANUAL 


viduals,  but  variations  from  these  accepted  positions  are 
common.     These  positions  are  well  worth  remembering  as 


Fig.  201.     Excavating  ulcer  of  lesser  curvature,  indicated  by  bracket. 

they  play  an  important  part  in  motility.    As  a  general  rule 
the  high  normal  stomach  empties  more  quickly  than  the 


GASTRO-INTESTIXAL  TRACT  443 

normal  fish-hook  type.     Function  is  more  important  than 
position. 

The  two  lesions  that  concern  us  chiefly  are  ulcer  and 
malignanc}^;  of  the  latter  carcinoma  is  by  far  the  most 
frequent.  The  signs  of  ulcer  of  the  stomach  are  as  fol- 
lows: 

1.  The  nicJie  and  accessory  pocket  are  seen  in  pene- 
trating ulcer.  The}'  appear  as  projections  from  the  gas- 
tric silhouette  and  vary  in  size  and  shape,  Fig.  200.  The 
vast  majority  of  ulcers  are  situated  on  the  lesser  curva- 
ture within  two  inches  of  the  pylorus.  Large  nonpenetrat- 
ing ulcers  can  be  readily  recognized  by  a  smooth,  shallow 
filling  defect,  Fig.  201.  Small  nonpenetrating  acute  ul- 
cers may  not  be  seen  directly,  but  can  often  be  recognized 
by  a  jumping  of  the  peristaltic  wave  and  by  tenderness  at 
that  area. 

2.  Hourglass. — The  organic  hourglass  is  the  result  of 
cicatrization  and  is  permanent. 

3.  Spasm. — There  are  tw^o  varieties:  general  and  local. 
The  local  simulates  organic  hourglass  in  contour  and  loca- 
tion, but  is  evanescent  in  character.  General  spasm  affects 
the  entire  stomach  so  that  there  is  an  absence  of  peristal- 
tic waves.  Both  can  be  overcome  by  paralyzing  the  mus- 
culature by  physiological  doses  of  atropine,  and  this  is  the 
only  method  by  which  the  spasmodic  hourglass  is  differen- 
tiated from  the  organic.  It  is  w^ell  to  remember  that  spas- 
modic hourglass  often  occurs  on  the  greater  curv^ature  op- 
posite a  gastric  ulcer,  Fig.  200. 

4.  Modified  Peristalsis. — There  is  usually  hyperperi- 
stalsis,  especially  in  the  early  part  of  the  examination,  as- 
sociated wdth  spasm  of  the  pylorus  and  consequent  delay 
in  expulsion. 

While  the  above  signs  ai^e  indicative  of  ulcer,  yet  it  is 
seldom  that  all  of  them  are  seen  in  the  same  case.    When, 


444 


U.  S.  ARMY  X-RAY  MANUAL 


Mg.  202.     Marked    dilatation    of    stomach    due    to    obstruction    at 
pylorus  (prone  position). 


GASTRO-INTESTINAL  TRACT  445 

for  instance,  the  ulcer  is  situated  at  the  pylorus,  causing 
obstruction  that  has  persisted  for  some  time,  spasticity  and 
hyperperistalsis  are  lost,  being  replaced  by  the  dilated 
atonic  stomach,  Fig.  202. 

Carcinoma  may  be  situated  in  any  portion  of  the  stom- 
ach, but  the  most  frequent  location  is  at  the  pyloric  end. 
Unlike  ulcer  at  the  pylorus  it  may  be  quite  extensive  with- 
out producing  obstruction. 

The  chief  signs  of  malignancy  are: 

1.  The  Filling  Defect. — An  irregular  serrated  defect 
due  to  the  projection  of  the  growth  into  the  lumen  of  the 
stomach,  Figs.  203  and  204. 

2.  Modified  Peristalsis. — The  infiltration  of  the  gas- 
tric wall  causes  a  diminution,  or  even  absence,  of  peristal- 
sis in  the  involved  area. 

3.  Emptying  Time. — When  obstruction  is  present,  the 
time  varies  according  to  the  degree  of  occlusion.  On  the 
other  hand,  it  may  happen  that  the  pyloric  ring  is  so  in- 
filtrated that  it  does  not  obstruct,  but,  on  the  contrary, 
cannot  contract,  and  then  there  is  rapid  clearance. 

When  growths  occur  on  the  greater  curvature,  the  les- 
ions manifest  themselves  by  filling  defects  of  varying  size. 
In  this  condition  the  function  of  the  stomach  is  so  little 
disturbed  that  an  early  clinical  diagnosis  is  often  impos- 
sible. On  this  account  this  region  is  spoken  of  as  the 
silent  area.  All  lesions  on  the  greater  curvature  should 
be  viewed  with  suspicion  as  to  malignancy,  as  ulcers  oc- 
cur almost  entirely  on  the  lesser  curvature.  In  carcinoma 
of  the  cardiac  end,  the  accompanying  esophageal  stenosis 
calls  the  patient's  attention  to  the  condition  and  renders 
an  early  clinical  diagnosis  possible.  Radiologically  this 
condition  is  recognized  by  a  varying  degree  of  obstruction 
at  the  cardia. 

Small    Intestine. — The    most    common     lesion    in    the 


446  U.  S.  ARiMY  X-RAY  MANUAL 

duodenum  is  ulcer.     The  chief  points  of  diagnosis  are  as 
follows : 

1.     Deformity  of  the  Duodenal  Bulb   (Cap). — This  re- 


FiG.  203,     Large  carcinoma  of  stomach.     The  large  filling  defect  is 
indicated  by  arrows. 

suits  either  from  spasm,  cicatrization,  adhesions,  or  from 
the  excavation  of  the  duodenal  wall  by  the  ulcer.  Fig. 
205. 


GASTRO-INTESTINAL  TRACT 


447 


2.     Gastric     Hyperperistalsis    and    Hypermotility. — In 
simple,  uncomplicated  cases  these  two   signs  are  usually 


f^  :^i: 


Fig.  204.     Carcinoma  of  stomach,  moderate  size,  indicated  by  bracket. 

observed  together.     In  acute  cases  they  are  practically  the 
only  signs. 

3.     Obstruction. — In  chronic  cases  the  marked  scar  for- 
mation may  so  encroach  upon  the  lumen  as  to  cause  vary^ 


448 


U.  S.  ARMY  X-RAY  MANUAL 


GASTRO-IXTESTIXAL  TRACT  449 

ing  degrees  of  obstruction  and  to  delay  the  emptying  time 
of  the  stomach. 

The  most  important  lesions  in  the  jejunum  are  angula- 
tion, which  will  be  discussed  later  under  adhesions,  and 
gastrojejunal  ulcers,  sometimes  seen  after  gastro-enteros- 
tomy.    Neither  of  these  lesions  occurs  frequently. 

In  the  ileum  the  most  frequent  abnormality  is  stasis. 
This  is  due  mainly  to  two  causes.  The  first  is  kinks  and 
adhesions,  the  second  is  reflex  spasm  in  cases  of  chronic 
appendicitis.  Kinks  and  adhesions  are  usually  situated 
about  two  to  six  inches  from  the  ileocolic  valve.  Spasm  is 
observed  in  the  extreme  terminal  portion  of  the  ileum,  al- 
most at  the  valve.  Kinks  and  adhesions  persist  at  the 
same  place  no  matter  what  the  position  of  the  patient  is. 
Angulations  may  be  noted  but,  unless  they  are  obstructive, 
they  are  of  no  importance.  The  most  extreme  degree  of 
stasis  occurs  in  tuberculous  peritonitis  due  to  adhesion 
throughout  the  abdominal  cavity. 

Colon. — Conditions  of  the  colon  which  lend  themselves 
best  to  x-ray  study  and  observation  are : 

Mucous  colitis,  diverticulitis,  malignancy,  obstruction, 
constipation,  adhesions  and  chronic  appendicitis. 

Mucous  colitis  is  characterized  by  remains  of  the  opaque 
meal,  incorporated  in  shreds  of  mucus-producing  material, 
casting  string-like  shadows.  They  are  most  commonly  seen 
in  the  descending  colon,  Fig.  206. 

Diverticulitis  is  characterized  by  small  circular  shadows 
beyond  the  lumen  of  the  colon,  seen  during  the  progress 
and  after  the  evacuation  of  the  barium  meal,  Fig.  207. 

Malignancy  is  characterized  by  filling  defects.  Figs.  208 
to  210.  This  may  be  either  annular  or  limited  to  one  side 
of  the  lumen.  The  filling  defect  may  be  seen  after  the 
ingestion  of  the  barium  meal,  but  is  best  shown  in  the  ma- 
jority of  cases  by  means  of  an  opaque  enema.     AYhenever 


450 


U.  S.  ARMY  X-RAY  MANUAL 


iP» 


Fig.  206.  Mucous  colitis  shown 
in  descending  colon  and  in  sigmoid, 
colon  up  to  splenic  flexure. 


by    stringy    shadow    of    barium 
Note  also  marked  spasticity  of 


GASTRO-INTESTINAL  TRACT  451 


Fig.  207.     Diverticulitis;    note    nearly    circular    shadows    seen    in 
transverse  and  descending  colon. 


452 


U.  S.  ARMY  X-RAY  MANUAL 


Fig.  208.     Carcinoma  of  ascending  colon   (ingested  mealj.     Arrow 
indicates  growth. 

a  filling  defect  is  observed  it  is  wise  to  repeat  the  examina- 
tion for  confirmation,  because  such  a  defect  may  be  simu- 
lated by  spasm  or  by  the  local  retention  of  feces  not  con- 
taining opaque  material. 

Obstruction. — In  acute  obstruction  the  site  of  the  lesion 


GASTRO-INTESTINAL  TRACT 


453 


-  iifftaa&Tn  I 


Fig.  209.     Carcinoma  of  hepatic  flexure  (enema).    Arrow  indicates 
growth. 

may  frequently  be  determined  without  the  administration 
of  barium  by  the  distended  gas-filled  bowel  above  the  les- 
ion. The  opaque  meal  is  absolutely  contra-indicated  and, 
when  the  opaque  enema  may  have  to  be  employed,  it  should 
be  used  with  the  greatest  care. 


454 


XT.  S.  ARMY  X-RAY  MANUAL 


Fig.   210.     Carcinoma  of  cecum    (enema).     Arrows  indicate  growth. 

Partial  Obstruction. — This  condition  is  seen  in  growths 
and  adhesions,  and  varies  according  to  the  degree  of  the 
encroachment  upon  the  lumen.  Dilatation  and  obstruc- 
tion should  be  looked  for.  The  opaque  meal  and  enema 
should  be  used,  especially  the  latter. 


GASTRO-INTESTINAL  TRACT  455 


Fig.  211.     Dyschezia;  note  dilatation  of  rectum  (ingested  meal). 

Dilatation,  distal  to  the .  lesion,  is  occasionally  seen  in 
patients  who  have  been  in  the  habit  of  taking  enemata. 
In  these  cases  the  sigmoid  and  rectum  are  especially  af- 
fected. 

Constipation  may  be  due  to  obstruction  or  may  be  func- 


456  IT.  S.  ARMY  X-RAY  MANUAL 

tional.  The  obstructive  varieties  have  already  been  dis- 
cussed in  the  preceding  paragraphs.  The  functional  va- 
riety is  best  studied  by  the  ingested  meal.  Two  principal 
types  are  recognized,  the  atonic  and  the  spastic.  The 
atonic  is  mainly  cecal  and  is  characterized  by  dilatation  of 
the  cecum  with  marked  retention  for  forty-eight  hours  or 
longer.  Spastic  constipation  most  frequently  involves  the 
transverse  or  descending  portions  of  the  colon  or  the  rec- 
tum. In  the  rectal  type,  known  as  dyschezia,  the  meal 
rapidly  passes  through  the  colon  into  the  rectum,  and 
stays  there  for  days,  gradually  producing  dilatation  of  the 
rectum,  Fig.  211.  Spasm  is  characterized  by  the  absence 
of  a  continuous  shadow  oi  the  barium,  by  a  diminution  in 
the  size  of  the  haustral  segments  and  by  an  increase  in  the 
depth  of  the  sulci. 

Adhesiotis  may  be  observed  in  any  part  of  the  gastro- 
intestinal tract,  but  are  more  commonly  found  at  the  fol- 
lowing points:  Stomach,  duodenum,  duodenojejunal  junc- 
tion, terminal  ileum,  cecum,  ascending  colon,  and  the  sig- 
moid. They  may  be  due  to  developmental  bands  or  be  the 
result  of  inflammatory  processes.  In  adhesions  at  the 
duodenojejunal  angle  there  is  dilatation  of  the  duodenum, 
Fig.  212,  and  reverse  peristalsis  after  digestion  is  well 
established. 

In  the  other  regions  mentioned  above,  fixation  is  the 
characteristic  feature  and  is  best  ascertained  by  palpation 
under  the  screen.  These  adhesions  may  distort  the  part 
so  as  to  cause  varying  degrees  of  obstruction. 

In  the  sigmoid,  obstruction  is  less  frequently  due  to 
adhesions,  but  rather  to  a  long  mesentery  which  allows  the 
sigmoid  to  drop  forward,  producing  an  angulation. 

Lower  Right  Quadrant. — In  addition  to  the  above-men- 
tioned lesions,  which  may  occur  here,  especial  attention 


GASTRO-INTESTINAL  TRACT 


457 


Fig.  212.     Angulation  at  duodenojejunal  junction,  causing  marked 
dilatation  of  third  portion  of  the  duodenum. 

should  be   directed   to  the   appendix  and  its  relation    to 
cecum  and  ileum. 

The  diagnostic  value  of  the  filling  or  nonfilling  of  the 
appendix  is  still  a  debatable  point.    When  the  appendix  is 


458 


U.  S.  AR]\rY  X-RAY  MANUAL 


jmmtam 


■■Uliiiii IIUIIII  II I  llllllllllllllllil  IIIIIIIIIIIIIIIIIMiiaMBi1^—i^—i— ^Eb^  - 

Fig.    213.     Appendix.      (Appendix   filled   with   barium.) 

visualized  observations  should  be  made  with  reference  to: 

1.  Size. — This   is  of  relatively  minor   importance. 

2.  Position. — When   the   appendix   is   curled   upon   it- 
self, retro-cecal,  or  its  tip  is  adherent  to  the  ileum  or  cecum, 


GASTROINTESTINAL  TRACT 


459 


Fig.  214.  Incompetency  of  ileocecal  valve.  Note  filling  of  small 
intestines  around  U.  X — marker  placed  on  rib  of  ensiform.  U — 
marker  placed  on  umbilicus. 


460 


U.  S.  ARMY  X-RAY  MANUAL 


Fig.  215. 
salts. 


Gall-stones.      Visible    because    of   presence    of    calcium 


it  may  be  regarded  as  pathological.    Mobility  and  fixation 
are  best  determined  by  palpation  under  the  screen. 

3.     Segmentation. — This  is  generally  regarded  as  an  in- 
dication of  previous  inflammation. 


GASTRO-INTESTINAL  TRACT  461 

4.  Tender  Spot. — Tenderness  elicited  over  the  region 
of  the  appendix  generally  means  a  pathological  condition 
in  this  area  and  is  of  especial  valne  when  the  appendix  is 
not  visualized. 

5.  Retention  in  the  Appendix. — Fig.  213.  Some  au- 
thors claim  that  retention  in  the  appendix  after  the  cecum 
is  empty  indicates  a  pathological  condition.  Other  observ- 
ers, however,  lay  more  stress  upon  ileal  retention. 

The  lower  right  quadrant  is  best  studied  by  means  of 
the  opaque  meal  at  the  time  the  cecum  is  filling.  The 
opaque  enema  is  of  no  value  except  in  the  determination 
of  the  position  of  the  cecum  or  of  the  competency  or  in- 
competency of  the  ileocecal  value,  Fig.  214. 

Gall-Bladder. — The  pathological  lesions  which  are  some- 
times observed  are  calculi,  adhesions,  and  distension-pro- 
ducing deformities  in  neighboring  organs,  especially  the 
duodenum. 

Calculi. — Those  containing  a  fair  amount  of  calcium 
salts  are  easily  recognized  by  their  nearly  circular  out- 
line, the  comparatively  dense  border  and  the  more  or  less 
transparent  central  portion,  Fig.  215.  Unfortunately 
these  form  a  relatively  small  percentage  of  the  total  num- 
ber of  gall-stone  cases.  Those  which  are  composed  of  pure 
cholesterin  are  difficult  to  demonstrate.  At  the  present 
day,  their  recognition  is  a  much  debated  question.  It  is 
not  in  the  scope  of  this  manual  to  discuss  the  claims  of 
various  observers  upon  this  subject.  A  safe  rule  for  the 
beginner  to  follow  is  not  to  diagnose  gall-stones,  except 
when  distinctly  shown  and,  conversely,  not  to  exclude  their 
presence,  if  none  have  been  demonstrated  on  the  plate. 

Adhesions  occur  most  commonly  between  the  gall-bladder 
and  duodenum.  They  can  be  recognized  by  palpation 
under  the  screen  after  an  invested  meal.    In  this  condition 


462  U.  S.  ARMY  X-RAY  MANUAL 

the  duodenum  will  be  fixed  in  the  upper  right  quadrant 
region  and  its  outline  will  sometimes  be  irregular. 

A  dilated  gall-bladder  occasionally  may  be  visualized, 
but  more  often  its  presence  is  detected  by  deformities  in 
neighboring  organs,  especially  in  the  duodenum.  The  de- 
formity in  the  duodenum  may  closely  simulate  that  pro- 
duced by  an  ulcer.  When  due  to  pressure  from  the  gall- 
bladder it  is  usually  not  accompanied  by  the  gastric  mani- 
festations seen  in  ulcer.  Sometimes  it  is  impossible  to  dif- 
ferentiate the  two  conditions. 


MEASUREMENT  OF  X-RAY  DOSE 

The  measurement  of  the  radiation  from  an  x-ray  tube 
has  been  the  subject  of  much  discussion  and  only  partial 
agreement  as  to  the  methods  that  should  be  employed  has 
been  attained  to  date.  A  satisfactory  method  would  en- 
able an  observer  to  determine  the  amount  of  radiation  de- 
livered by  the  tube  in  a  simple  and  effective  manner,  and 
would  enable  others  to  reproduce  results  without  requir- 
ing unusual  skill  or  loss  of  time. 

It  is  certain  that  a  proper  measurement  of  current,  ef- 
fective voltage  at  the  tube  terminals,  time  of  exposure,  dis- 
tance between  target  and  skin,  nature  and  amount  of  fil- 
tration through  which  the  rays  pass  before  reaching  the 
skin  give  all  the  data  necessary  for  the  reproduction  of 
x-ray  dose.  This  method,  however,  has  not  appealed  to  the 
profession  as  yet,  partly  because  there  is  no  record  actu- 
ally produced  by  the  radiation  to  which  the  attention  of 
the  physician  or  his  assistant  may  be  directed.  A  state- 
ment, however,  of  the  approximate  conditions  under  which 
fairly  w^ell  established  doses  may  be  obtained  is  of  consid- 
erable service  as  supplementing  the  reading  by  radiometers. 

Of  the  various  effects  produced  by  x-rays  only  two  have 
found  a  reasonable  amount  of  favor  as  a  basis  for  measure- 
ment. These  are  (1)  the  effect  upon  the  photographic  emul- 
sion, (2)  the  color  change  of  platinum  barium  cyanide  crys- 
tals when  exposed  to  the  radiation.  The  latter,  or  pastille 
method  was  first  proposed  by  Saboraud  and  Noire  who  es- 
tablished a  color  to  be  attained  by  the  pastille  when  it 
receives  an  amount   of  radiation  sufficient,   generally,  to 

463 


464  U.  S.  ARMY  X-RAY  MANUAL 

produce  a  slight  inflammation  of  the  skin  or  an  ''erythema" 
dose.  The  method  was  further  studied  by  Holzkneeht, 
Hampson,  and  others,  partly  with  the  idea  of  enabling  one 
to  read  fractional  doses.  In  order  to  do  this  it  is  neces- 
sary to  have  a  scale  of  colors  or  tints  corresponding  to 
those  attained  by  the  pastille  in  various  stages  of  expo- 
sure. In  using  the  pastille  method  there  are  several  pre- 
cautions which  should  be  observed.  Among  these  may 
be  mentioned  the  following: 

(a)  The  pastille  will  change  from  an  apple  green  tint 
toward  the  brownish  yellow  produced  by  the  action  of 
x-rays  under  the  action  of  bright  sunlight  or  heat,  or  even 
in  an  extremely  dry  atmosphere.  For  this  reason  the  pas- 
tille should  be  kept  in  a  suitable,  ventilated  humidor  in 
diffuse  daylight  and  not  near  radiators  or  other  heating 
devices. 

(b)  After  use,  when  placed  in  an  ordinary  moist  atmos- 
phere, not  in  heat  or  bright  sunlight,  or  in  strong  artificial 
light,  the  pastilles  tend  to  regain  their  original  unradiated 
tint  though  they  rarely  completely  recover.  For  this  rea- 
son the  reading  should  be  made  immediately  after  expo- 
sure and  the  result  recorded. 

(c)  Inasmuch  as  the  tint  reading  depends  upon  an  ac- 
curate perception  of  color  difference  the  method  is  unsuit- 
able for  people  who  are  partially  color  blind,  especially 
in  the  green.  Also  since  the  pastille  cannot  reflect  light 
to  the  eye  that  it  does  not  receive,  it  must  be  read  in  a 
fairly  standard  illumination.  The  best  light  available  for 
this  purpose  is  that  from  a  low  power  carbon  filament 
lamp;  the  observation  should  be  made  by  reflected  light 
and  the  eyes  shielded  from  direct  illumination  from  the 
the  lamp.  Care  should  be  taken  that  the  gloss  or  sheen  of 
the  pastille  does  not  confuse  the  reading. 

(d)  There  are  two  positions  used  by  different  observers 


MEASURE.MENT  OF  X-RAY  DOSE  465 

for  exposure  of  these  pastilles.  They  may  be  placed  either 
on  the  patient's  skin  where  the  radiation  strikes  or  half- 
way between  the  skin  and  the  target.  The  amount  of  skin 
dose  indicated  by  the  same  change  of  color  of  the  pastille 
placed  on  the  skin  is  four  times  as  great  as  when  the 
pastille  is  at  the  half-distance  point.  The  advantage  of  the 
skin  position  is  certainty  of  distance  from  target  to  skin. 
A  slight  error  in  estimating  the  distance  from  the  target  to 
the  skin  for  comparison  with  the  pastille  at  the  half  dis- 
tance may  introduce  a  relatively  large  error  in  dosage. 
Also  the  moderate  changes  of  color  are  read  more  accu- 
rately than  the  extreme  changes,  partly  because  they  change 
less  rapidly  after  exposure. 

(e)  While  a  pastille  may  be  used  a  second  or  third  time 
it  is  unwise  to  do  so.  It  is  far  better  to  depend  on  elec- 
trical measurements,  time  and  distance  than  to  use  a  poor 
pastille  or  radiometer. 

(f)  The  comparison  tints  of  a  radiometer  are  not  per- 
manent and  two  of  the  same  make  rarely  agree.  The  Hamp- 
son  0  will  rarely  agree  with  the  tint  of  a  fresh  pastille 
and  if  too  yellow  the  pastille  must  be  brought  to  agree  with 
a  low  numbered  scale  tint  before  use.  The  reading  is  then 
made  by  subtracting  the  number  before  treatment  from 
that  of  the  match  tint  after  treatment.  Thus  if  the  pas- 
tille matches  tint  3  before  and  number  7  afterwards  the 
dose  is  4  Ha. 

The  photographic  method  has  generally  been  spoken  of 
as  the  Kienbock  method  and  involves  the  use  of  a  photo- 
graphic paper  of  the  proper  degree  of  sensibility.  It  is 
essential : 

(a)  That  the  paper  should  be  uniform  in  sensibility 
and  carefully  kept. 

(b)  That  development  be  carefully  attended  to  w^ith 
reference  to  nature   and  concentration  of  developer,   its 


466 


U.  S.  AR.MY  X-RAY  IMANUAL 


temperature  and  the  time  of  development.  Of  these  it 
may  be  remarked  that  variation  in  temperature  is  the 
most  important,  variation  in  time  of  development  is  next, 
and  within  reasonable  limits  concentration  of  developer 
has  little  effect.  The  advantage  of  this  method  lies  in  the 
fact  that  it  gives,  when  properly  done,  a  permanent  record 


1       2      5     4       56763     10— X     ^ 
i  2  5  4  b—HWj 

Fig.  216.     Dosage  curve  for  various  spark  gaps. 


of  superficial  dose.  The  disadvantages  are  variation  in 
sensibility  of  paper  (which  are,  however,  no  greater  than 
that  of  pastilles),  and  the  need  of  care  and  attention  in 
development. 

The  paper  method  is  extremely  useful  in  determining 
whether  or  not  an  x-ray  operator  is  receiving  more  than 
a  safe  amount  of  radiation.  It  is  superior  to  the  pastille  for 
this  purpose,  owing  to  the  fact  that  it  may  be  carried  for 
a   considerable   period   of  time   attached  to  the   clothing, 


MEASUREMENT  OF  X-RAY  DOSE  467 

if  properly  protected  from  light,  and  be  unaffected  by  any- 
thing excepting  the  x-rays  received.  A  scale  in  X  units 
may  be  readily  worked  out  using  the  data  of  curve,  Fig. 
216,  and  it  will  have  very  much  the  appearance  of  Fig. 
52  for  determination  of  the  sensibility  of  intensifying 
screens.  Inasmuch  as  10  X  corresponds  to  an  erythema 
dose,  it  is  very  easy  to  make  such  a  strip  in  which  the 
different  portions  will  receive  from  1  to  10  X  units.  If 
a  series  of  small  pieces  of  this  paper  are  placed  in  a  light 
proof  container  transparent  to  x-rays  and  attached  to  the 
clothing  in  regions  likely  to  receive  either  direct  or  scat- 
tered radiation  or  both,  they  may  be  removed,  one  at  a 
time,  at  successive  intervals  and  developed  under  the  same 
conditions  prevailing  when  the  scale  was  made  and  the 
rate  at  which  radiation  was  received  per  hour  determined. 
(See  also  chapter  on  dangers  and  protection,  page  194.) 
It  must  be  understood  that  the  radiometer  gives  an  in- 
dication of  the  radiation  it  absorbs  from  the  incident  beam 
and  does  not  tell  how  much  is  going  to  reach  anj^  given 
depth.  This  will  be  dependent  upon  the  voltage  at  which 
the  tube  is  operated  and  upon  the  amount  of  filtration  be- 
tween the  target  and  the  skin. 

The  radiometer  available  in  the  army  base  hospital  at 
present  is  the  Hanipson.  A  graded  series  of  tints  is 
mounted  on  a  circular  disc  that  revolves  past  a  small  open- 
ing. These  tints  are  numbered  from  0  to  24  and  a  match  is 
to  be  made  by  placing  the  radiated  pastille  as  near  as  pos- 
sible to  the  opening  where  the  tints  appear  and  rotating 
the  disc.  Instructions  will  be  found  with  the  instrument. 
If  the  pastilles  supplied  are  brownish  or  yellow  instead 
of  pale  green  they  are  old  and  have  not  been  properly 
kept.  It  would  be  safer  to  use  the  data  of  Fig.  216  care- 
fully adjusting  for  current  and  gap  rather  than  to  depend 
upon  poor  pastilles. 


468  U.  S.  ARI\IY  X-RAY  MANUAL 

If  the  reader  desires  to  translate  instructions  for  ther- 
apy from  one  scale  to  another  the  relations  are  as  follows, 
assuming  that  we  have  a  fresh  pastille: 

Position 
Designation     Author         of  pastille  on  strip 

Erythema  Dose  Tint  B   Saboraud     %  target  skin  distance 
5  H    Holzknecht  I/2  target  skin  distance 
114  H    Holzknecht  Pastille  on  the  skin 
10  X    Kienbock      Strip  on  the  skin 
4  Ha  Hampson      Pastille  on  the  skin 
16  Ha  Hampson     Pastille  at  %  distance. 

The  curve,  Fig.  216,  shows  the  unfiltered  dose  when  5 
ma.,  8  inches  target  skin  distance,  is  used  for  30  seconds, 
for  various  spark  gaps  between  moderately  blunt  points. 
The  time  may  be  varied  to  compensate  for  any  current  that 
may  be  used  with  the  selected  gap.  Thus  at  10  ma.,  15 
seconds  will  be  required,  at  3  ma.,  50  seconds,  etc. 


CUTANEOUS    X-RAY   THERAPY 

Not  to  he  Administered  hy  the  X-ray  Manipulators  Unde 

am  J   nirrAj.n}.<ifnnr,p,s 


any  Circumstances 


Explanations. — In  this  chapter  Holzknecht  nnits  are 
estimated  with  the  pastille  on  the  skin ;  symbol  H. 

Filtration. — Aluminum  3  mm.  Dose  estimated  with  pas- 
tille on  skin  and  covered  with  the  filter. 

Erythema  Dose. — Synonyms :  skin  toleration  dose ;  epi- 
lating  dose :  skin  unit.  A  quantity  of  ray  sufficient  to  pro- 
duce defluvium  of  scalp  hair.  The  same  quantity  will 
l^rovoke  erythema  on  most  parts  of  the  cutaneous  envelope. 
Expressed  in  figures :  li/4  H ;  4  Hampson ;  10  X. 

Intensive  Treatynent. — Single  exposures,  at  monthly  in- 
tervals, to  one  area,  of  quantity  ranging  from  H  1  to  H  2 
unfiltered  and  from  H  2  to  H  3  filtered. 

Semi-intensive  Treatment. — H  %  at  intervals  of  2  weeks 
(H  1  filtered). 

Fractional  Treatment. — H  %  or  H  1^4  once  or  twice 
weekly  (H  14  or  H  1/0  filtered). 

Quality. — The  majority  of  skin  diseases  respond  better 
to  rays  of  comparatively  short  wave  length.  For  routine 
technique  employ  a  spark  gap  of  6  or  7  inches.  For  fil- 
tered treatments  use  a  9-incli  gap. 

Protection  to  Patients. — Protect  healthy  skin,  testicles, 
hairy  parts,  etc.,  with  lead  foil  or  other  suitable  material 
containing  an  aperture  the  size  of  the  lesion. 

Radiodermatitis. — Definition.    A  reaction  on  the  part 

469 


470  U.  S.  ARMY  X-RAY  MANUAL 

of  the  skin   (and  siibentaneous  tissue)   to  the  influence  of 
the  x-ray.    Divided  into  3  degrees. 

First  Degree. — Erythema  which  may  be  faint  and  tran- 
sient; or  pronounced,  enduring  for  several  weeks  and  ac- 
companied by  burning,  stinging,  itching  and  temporary  or 
permanent  loss  of  hair.  Frequently  leaves  pigmentation 
which  may  persist  for  many  months. 

Second  Degree. — Erythema,  exfoliation,  vesiculation,  ex- 
coriation, exudation  and  burning  pain.  Requires  several 
weeks  to  heal. 

Third  Degree. — All  the  second  degree  symptoms,  ending 
in  indolent  ulceration  with  destruction  of  true  skin,  sub- 
cutaneous tissue  and  even  the  muscles.  Excruciating  pain. 
Requires  months  and  even  years  to  heal. 

Severe  Reactions. — These  usually  appear  a  day  or  two 
after  exposure.  Conversely,  mild  reactions  are  first  mani- 
fested from  7  to  10  days  subsequent  to  the  treatment. 
This  is  not  always  so.    The  reverse  may  be  true. 

Delayed  Reactions. — Occasionally  a  reaction  does  not  ap- 
pear until  after  a  lapse  of  3  or  4  weeks. 

Electrical  Erythema. — This  is  an  erythema  occurring 
within  from  3  to  8  hours  and  lasting  a  day  or  two.  Ac- 
cording to  Pfahler  it  can  be  avoided  by  grounding  the 
lead  foil  used  to  protect  the  normal  skin. 

Sequelw. — A  single  occurrence  of  a  simple  erythema  may 
give  rise,  6  months  or  a  year  later,  to  telangiectasia,  atrophy 
and  alopecia.  Therefore  erythema  of  the  exposed  parts 
should  be  avoided.  Second  degree  reactions  usually  leave 
atrophy,  telangiectasia  and  alopecia.  Years  later  keratoses 
may  develop.  Repeated  erythema  also  may  effect  these 
sequelae.  Third  degree  reactions  may  never  heal.  If  they 
do  the  resulting  scar  is  unhealthy,  even  dangerous. 

Etiology. — With  the  exception  of  idiosyncrasy  and  ac- 
quired susceptibility  the   cause   of  radiodermatitis   is  ex- 


CUTANEOUS  X-RAY  THP:RAPY  471 

cessive  dosage.    It  is  a  question  of  quantity,  not  of  quality. 
Idiosijncrasy. — True   idiosyncrasy   is   a   very   rare   phe- 
nomenon.    Acquired   hypersusceptibility   is  common.     To 
avoid  unexpected  reactions  observe  the  following  rules : 

1.  Technique  must  be  in  accordance  with  modern  re- 
quirements. 

2.  Unless  specifically  indicated  avoid  large  doses. 

3.  Allow  sufficient  time  between  doses. 

4.  Very  young  individuals  react  more  vigorously  than 
do  old  people.  The  skin  of  brunettes  is  less  sensitive  than 
that  of  blonds,  that  of  females  a  little  more  than  that  of 
males. 

5.  The  flexor  surfaces  are  more  sensitive  than  the  ex- 
tensor surfaces.  The  flexures  and  skin  over  the  joints  are 
very  sensitive.     The  face  is  exceedingly  sensitive. 

6.  Chemicals  such  as  mercury,  iodine,  tar,  iodoform, 
chrysarobin,  sulphur,  etc.,  applied  before  or  after  treat- 
ment markedly  enhance  the  influence  of  the  ray.  At 
times  this  effect  may  endure  for  weeks  and  months. 

7.  Skin  affected  by  certain  diseases — psoriasis,  eczema, 
acute  lichen  planus,  mycosis  fungoides — is  hypersensitive. 

8.  Acute  inflammations  and  the  congestive  dermatoses 
react  more  severely  than  do  lesions  containing  a  poor  blood 
supply  or  those  that  are  covered  by  a  thickened  horny 
layer. 

Treatment.— ^h^re  is  no  known  practical  procedure  that 
will  prevent,  modify  or  abort  a  reaction  after  the  treatment 
has  been  given.  Nor  is  there  any  way  to  avoid  the  de- 
velopment of  sequelae.  First  degree :  Use  10  per  cent  zinc 
oxide  ointment.  Second  degree :  Use  wet  dressing  of  alu- 
minium acetate ;  do  not  allow  exudate  to  come  in  contact 
with  normal  skin — severe,  generalized,  exudative  eczema 
may  result.     Third  degree:     If  deep  and  indolent,  excise 


472  U.  S.  ARMY  X-RAY  ]\IANUAL 

the  area.  Otherwise,  use  wet  dressings  or  a  10  per  cent 
zinc  oxide  ointment  containing  1  per  cent  of  ichthyol.  For 
the  pain,  10  per  cent  of  anesthesin  may  be  added  to  the 
ointment  or  wet  dressing. 

Biology. — The  x-ray  exerts  its  greatest  influence  on  cells 
that  are  either  physiologically  or  biologically  very  active. 
The  nearer  a  cell  approaches  the  embryonic  type  (the 
more  recent  its  development)  the  greater  is  its  susceptibility 
to  the  x-ray.  This  explains  the  profound  influence  of  the 
ray  on  the  function  of  the  ovary  and  testicle,  also  on  the 
glandular  structures  of  the  skin,  the  germinating  layer  of 
the  epidermis,  etc.  Many  cutaneous  diseases  consist,  his- 
tologically, of  a  rapid  multiplication  of  cells — these  active 
cells  are  likely  to  be  easily  influenced  by  the  ray.  Bacteria 
are  not  affected  by  practical  doses.  The  soil,  however,  may 
be  so  modified  as  to  interfere  seriously  with  bacterial  de- 
velopment. 

Bragg  advances  the  theory  that  the  biologic  action  of 
the  x-ray  or  gamma  ray  depends  upon  ionization — a  disso- 
ciation of  the  elements  comprising  the  cell — also,  that  most 
of  this  ionization  is  accomplished  by  the  corpuscular  sec- 
ondary rays  (beta  rays)  formed  in  the  tissue.  These  rays 
are  a  product  of  the  primary  beam,  of  the  scattered  rays 
and  of  the  characteristic  rays.  It  may  be,  therefore,  that 
the  sole  purpose  of  the  x-ray  is  to  penetrate  the  tissues  and 
produce  beta  rays  at  the  desired  depth. 

Stimulation  and  Inhibition. — As  shown  by  botanical  ex- 
periments small  doses  at  long  intervals  stimulate  embryonic 
tissue ;  large  doses  inhibit  and  destroy.  This  knowledge  can 
be  utilized  in  the  application  of  x-ray  to  disease. 

Diseases  and  Conditions 

Eczema. — The  x-ray  is  of  benefit  in  practically  all  but 
the  very  acute  types  of  this  affection.    Subacute  or  chronic 


CUTANEOUS  X-RAY  illERAPY  473 

eczema,  whether  squamous  or  exudative,  especially  when 
occurring  in  patches,  yields  with  amazing  rapidity.  Sebor- 
rheic eczema  and  chronic  occupational  eczema  also  are 
markedly  benefited.  The  lesions  of  eczema  disappear  un- 
der the  influence  of  the  ray  but  the  disease  itself  remains 
unaffected. 

Technique. — Fractional.  H  Yg  once  or  twice  weekly.  If 
this  does  not  cause  involution  in  2  or  3  weeks,  do  not  in- 
crease nor  persist  in  the  treatment. 

Psoriasis. — Psoriasis  of  any  type  yields  promptly,  as  a 
rule,  to  the  x-ray. 

Technique. — Widely  separated  patches  are  to  be  shielded 
closely  and  treated  individually;  fractionally  or  semi-in- 
tensively.  Generalized  eruption  necessitates  treatment  of 
most  of  the  body  surface  including  normal  skin  between 
lesions.  Divide  body  into  sections  as  follows:  1.  Scalp, 
face,  neck.  2.  Chest,  abdomen.  3.  Dorsal  back,  lumbar 
back,  buttocks.  4.  Thighs  (4  surfaces).  5.  Legs  and 
feet  (2  surfaces).  6.  Arms,  forearms  and  hands  (2  sur- 
faces). To  avoid  overlapping,  mark  dividing  lines  with  a 
skin  pencil.  Expose  one  section  daily  with  fractional  dose 
of  H  Yg.  No  one  section  is  to  receive  more  than  one  treat- 
ment in  one  week.  After  the  second  week,  if  improvement 
is  not  satisfactory,  increase  to  H  ^.  If  disease  is  not  un- 
der control  in  four  or  six  weeks  discontinue  treatment. 
When  the  lesions  have  disappeared  stop  treatment — do  not 
treat  the  remaining  stains.  If,  during  treatment,  a  toxic 
rash  appears,  discontinue  treatment  immediately.  The 
scalp  is  to  be  treated  in  accordance  with  the  Kienbock- 
Adamson  method  (see  page  480),  the  dose  being  as  above 
stated.  For  the  face  the  tube  is  placed  first  over  the  zygoma 
on  one  side  and  then  over  the  other  side.  Scalp, 
eyes,  eyebrows  and  eyelashes  must  receive  protection.  The 
neck  will  receive  enough  ray  from  the  scalp  and  face  treat- 


474  U.  S.  ARMY  X-RAY  MANUAL, 

ments.  In  treating  section  2  place  tube  consecutively  over 
a  point  a  little  outside  and  above  one  nipple,  same  position 
on  other  side,  5  inches  to  one  side  of  umbilicus  and  same 
distance  to  opposite  side.  Allow  the  rays  from  these  treat- 
ments to  overlap,  but  do  not  allow  one  section  to  overlap 
another.  Apply  same  general  scheme  to  treatment  of  sec- 
tion 3.  Anterior,  posterior  and  lateral  surfaces  of  thighs 
often  must  be  exposed.  In  treating  these  the  surface  angle 
of  incidence  of  one  exposure  should  be  at  right  angles  to 
any  other.  The  flanks  wall  receive  sufficient  ray  from  the 
back  and  abdomen  exposures.  When  extremities  are  very 
long  it  may  be  necessary  to  make  two  exposures  to  one 
surface.  For  example,  a  long  thigh,  the  tube  is  first  placed 
over  the  upper  part  and  then  over  the  lower  part,  the  rays 
being  allowed  to  overlap  in  the  center.  In  such  instances 
the  exposures  should  be  10  inches  apart.  X-ray  cures  the 
lesions  not  the  disease. 

Dermatitis  Exfoliativa. — This  is  often  secondary  to 
eczema  or  psoriasis — when  these  diseases  become  universal. 
This  type  usually  responds  well  to  technique  outlined  for 
psoriasis.  The  primary  type  is  more  recalcitrant,  but  often 
undergoes  involution  under  x-ra}^  therapy. 

Lichen  Planus. — This  disease  causes  severe  itching 
which  is  exceedingly  difficult  to  control.  Under  ordinary 
dermatological  treatment  from  three  to  eight  months  is  re- 
quired to  effect  a  cure.  X-ray  treatment  will  usually  af- 
ford prompt  relief  from  the  itching  and  will  make  the 
eruption  disappear  in  from  two  to  eight  weeks. 

Technique. — Chronic  localized  patches  are  shielded  close 
and  treated  fractionally  (H  i/i  once  weekly)  semi-inten- 
sively  or  intensively.  A  single  intensive  dose  of  H  %  to 
H  1  will  often  suffice.  Acute  generalized  lichen  should  be 
managed  as  generalized  psoriasis.  The  dose  must  be  small ; 
H  i/«. 


CUTANEOUS  X-RAY  THERAPY  475 

Lichen  Chronicus  Circumscriptus  and  Lichenification. — 

These  affections  respond  promptly  to  fractional  doses  of 
H  1/4  weekly. 

Pompholyx  (Dysidrosis). — Fractional  treatment  is  of 
distinct  service. 

Clavus,  Callositas,  Verrucae. — Corns  (hard  or  soft)  re- 
spond to  from  1  to  3  intensive  treatments.  Remove  horny 
layer  with  razor,  shield  verj^  close  and  apply  HI.  If 
horny  layer  is  still  thick  after  use  of  razor  H  li/o  may  be 
applied.  The  exceedingly  painful,  so-called  plantar  wart 
responds,  as  a  rule,  to  one  or  two  treatments.  The  tech- 
nique is  the  same  as  in  the  treatments  of  corns.  If  three 
treatments  do  not  result  in  a  cure  advise  some  other  form  of 
treatment.  The  common  wart  (verruca  vulgaris)  usually 
responds  to  one  intensive  treatment  of  from  H  1  to  H  II/2. 
Shield  very  close.  Do  not  give  more  than  two  treatments. 
The  flat  wart  (verruca  planum)  does  not  respond  well  to 
radiotherapy.  Senile  warts  (A^erruca  senilis,  verruca  sebor- 
rheica, etc.)  disappear  as  a  result  of  a  single  treatment  of 
H  2  providing  the  horny  layer  is  first  removed.  These  le- 
sions are  potentially  dangerous,  therefore  they  must  not  be 
stimulated.    Do  not  shield  too  close. 

Keloids,  Hypertrophic  Scars,  Cicatricial  Tissue,  Etc. — 
With  the  exception  of  radium  the  x-ray  is  the  only  means 
of  successfully  treating  a  keloid.  Small  recent  keloids  dis- 
appear in  one  or  two  treatments.  Large,  hard,  old  keloids 
may  require  eight,  ten  or  twelve  treatments.  Spontaneous 
keloids  are  less  recalcitrant  than  are  those  developing  sec- 
ondary to  definite  trauma.  Hypertrophic  scars  and  cica- 
tricial bands  can  be  softened,  reduced  and  even  completely 
absorbed. 

Technique. — Shield  right  up  to  the  very  edge  of  the  le- 
sion. Emplo}^  the  intensive,  filtered  technique,  but  do  not 
cause  an  erythema.     If  the  first  treatment  provokes  a  vis- 


476  U.  S.  ARMY  X-RAY  MANUAL 

ible  reaction,  reduce  the  size  of  the  subsequent  doses.  If 
lesions  are  small,  filtration  is  not  necessary.  In  cases  where 
eight  or  ten  treatments  are  required  care  must  be  taken  not 
to  produce  an  x-ray  skin.  This  can  be  done  by  avoiding 
erythema  and  by  allowing  intervals  of  two  or  three  months 
between  treatments.  If  the  lesion  is  very  large  and  pedun- 
culated, it  should  be  excised  and  x-ray  used  as  a  prophylac- 
tic. Do  not  administer  the  x-ray  immediately  after  the 
operation — allow  an  interval  of  two  or  three  weeks.  Frac- 
tional and  semi-intensive  treatments,  also,  give  good  results 
in  keloidal  tissue. 

Plastic  Surgery. — Quite  recently  Percival  Cole  and 
Knox  have  found  the  x-ray  of  service  in  preparing  gun- 
shot wounds  for  plastic  operations.  In  extensive  wounds, 
especially  those  involving  the  orifices,  there  is  formed  con- 
siderable thick,  inelastic  cicatricial-  tissue.  This  tissue  is 
rendered  considerably  softer  by  from  one  to  three  inten- 
sive treatments. 

These  authors  have  also  employed  the  ray  to  depilate  hair 
when  a  flap  of  skin  is  going  to  be  utilized  to  replace  the 
destroyed  lining  of  a  cavity  such,  for  instance,  as  the 
mouth.  It  is  necessary  in  such  instances  to  effect  perma- 
nent alopecia  and  this  must  be  done  without  too  much 
injury  to  the  skin.  It  is  practically  impossible  to  produce 
a  permanent  alopecia  without  a  little  atrophy,  and  we  may 
even  get  a  little  telangiectasia.  These  sequelae  are  of  no 
importance.  But  repeated  reactions  of  the  first  degree  and 
a  single  reaction  of  the  second  degree  must  be  avoided.  It 
is  preferable  to  avoid  even  a  first  degree  reaction.  If  only 
a  small  flat  area  of  the  bearded  region  is  to  be  used  as  a 
flap,  and  this  is  generally  the  case,  one  treatment  (H  li/4 
filtered  through  1  mm.  Al.,  7  to  9-inch  spark  gap)  will 
usually  make  the  hair  fall  out,  but  it  may  also  provoke  an 
erythema.     There  is  less  likelihood  of  a  reaction  if  this 


CUTANEOUS  X-RAY  THERAPY  477 

amount  of  x-ray  is  divided  into  fractions  and  administered 
during  a  period  of  two  or  three  weeks.  After  the  deflu- 
vium  it  is  necessary  to  administer  H  1  monthly  or  H  i/o  bi- 
monthly for  from  three  to  six  months  to  insure  against  a 
regrowth  of  hair. 

Tuberculosis. — This  disease  is  multiform  in  its  cutaneous 
manifestations,  and  these  various  manifestations  are  di- 
vided into  a  number  of  clinical  entities,  as  follows: 

Lupus  Vulgaris. — Atrophic,  hypertrophic  and  ulcera- 
tive. The  hypertrophic  and  ulcerative  forms  do  very  well 
under  x-ray  treatment.  It  is  possible  to  obtain  a  perma- 
nent cure.    The  atrophic  type  is  exceedingly  rebellious. 

Technique. — Intensive. 

Lupus  Erythematosus. — Discoid  and  disseminate.  Oc- 
casionally this  disease  (which  is  not  true  tuberculosis)  will 
respond  to  the  x-ray;  usually  it  will  not  do  so.  A  larger 
percentage  of  cases  yield  to  the  more  penetrating  radium 
beta  rays;  and  these  rays  often  fail.  The  discoid  type  is 
less  recalcitrant  than  is  the  disseminate  type.  The  dis- 
ease when  "cured"  always  recurs. 

Technique. — Fractional,  semi-intensive  or  intensive  in  the 
discoid  form ;  fractional  in  the  disseminate  type. 

Caution. — Remember  that  both  lupus  vulgaris  and  lupus 
erythematosus  yield  slowly — that  considerable  treatment  is 
required.  Remember,  too,  that  both  these  diseases  leave  a 
scar  in  which  cancer  is  prone  to  develop.  Therefore  do  not 
persist  in  the  treatment  of  the  lesion,  if  it  does  not  yield 
to  a  few  mildly  intensive  treatments  or  the  equivalent  in 
fractional  doses.    Do  not  produce  an  x-ray  skin. 

Tuberculosis  Verrucosa  Cutis  (Warty  Tuberculosis — ■ 
Anatomical  Tubercle). — This  affection  usually  undergoes 
involution  rather  promptly  under  the  influence  of  intensive 
treatment.  If  the  verrucose  element  is  marked  use  a  filter. 
A  permanent  cure  may  be  expected. 


478  U.  S.  ARMY  X-RAY  INIANUAL 

Baziivs  Disease  and  Sarcoid. — Good  results  may  be  ob- 
tained by  fractional,  semi-intensive  or  intensive  filtered 
treatments,  preferably  the  latter. 

Tuberculosis  Orificialis. — Tuberculosis  of  the  orifices 
usually  does  well  under  x-ray  therapy — intensive  doses. 
Because  of  the  location,  radium  is  often  preferable.  Re- 
lapses are  common. 

Tuberculous  Adenitis. — Good  results  may  be  expected 
in  a  fair  percentage  of  cases. 

Technique. — Intensive  or  semi-intensive  filtered  treat- 
ments. In  cervical  adenitis  do  not  provoke  an  erythema 
because  of  the  possibility  of  subsequent  telangiectasia. 

Epithelioma. — Basal  cell  (rodent  ulcer)  and  squamous 
cell  (malignant).  In  the  basal  cell  type  a  permanent  cure 
may  be  expected  in  from  85  to  90  per  cent  of  unselected 
cases.  The  result  is  always  doubtful  in  the  squamous  cell 
type.  If  the  basal  cell  type  is  given  a  preliminary  curet- 
tage a  cure  can  usually  be  obtained  in  one  or  two  treat- 
ments. It  is  unwise  to  curette  the  squamous  cell  type  be- 
cause of  the  danger  of  metastasis.  The  lesion  should  be  re- 
moved by  a  wide  excision  and  the  entire  region  and  neigh- 
boring glands  given  several  intensive  filtered  treatments. 

Technique. — Very  intensive  (H  2  or  H  21/2  unfiltered). 
If  the  lesion  is  markedly  infiltrated  and  is  not  curetted,  em- 
ploy a  filter  .  Always  include  a  wide  area  around  the  le- 
sion. Do  not  stimulate.  Stimulation  can  be  avoided  by  in- 
tensive treatment,  by  curettage,  by  cross-fire  when  possible, 
filtration  when  desirable,  and  by  dividing  large  lesions  into 
from  2  to  4  squares  and  applying  an  intensive  dose  to  each 
square.  If  a  full  dose  is  administered  to  the  center  of  a 
large  lesion,  the  margin  may  be  stimulated  (intensity  in- 
verse as  square  of  distance).  In  deep  lesions,  on  ac- 
count of  absorption,  the  lowermost  cells  may  be  stimulated 
unless  lesion  is  curetted,  a  filtered  ray  is  employed  or  the 


CUTANEOUS  X-RAY  THERAPY  479 

cross-fire  method   (administration  of  full  doses  to  a  tumor 
from  two  or  more  directions)  utilized. 

Sarcoma. — As  in  ei)itli('li()in;i,  tliere  are  benign  and  ma- 
lignant forms  of  sarcoma.  The  benign  types  (Kaposis  sar- 
coma, the  Speigler  type,  etc.)  usually  respond  readily.  The 
malignant  types  frequentl}^  do  well  if  stimulation  is 
avoided.  The  technique  is  the  same  as  in  the  squamous 
cell  sarcoma. 

Mycosis  Fungoides. — The  lesions  of  this  terrible  dis- 
ease, both  in  the  premycotic  and  the  fungoid  stages,  dis- 
appear  in  the  most  surprising  manner  under  the  influence 
of  the  x-ray.  In  fact  they  undergo  such  prompt  involu- 
tion that  caution  must  be  exercised  in  order  to  prevent 
systemic  toxemia.  The  distressing  itching  is  usually  re- 
lieved at  once.  The  disease  cannot  be  cured,  but  it  is 
often  possible,  by  occasional  treatment,  to  keep  an  indi- 
vidual alive  and  comfortable  for  many  years. 

Technique. — The  technique  is  the  same  as  that  described 
under  psoriasis.  The  dose  at  first  should  be  very  small 
(H  1/16  to  H  Yg) .  Later  this  may  be  increased  to  H  14. 
If  a  toxic  rash  appears  or  there  are  any  symptoms  of  tox- 
emia, discontinue  treatment  at  once.  After  these  symptoms 
disappear  begin  again  and  proceed  cautiously,  ^hen  the 
disease  is  under  control,  and  one  or  two  lesions  develop  at 
long  intervals  it  is  permissible  to  employ  a  mildly  inten- 
sive technique. 

Acne  Vulgaris. — The  x-ray  is  a  specific  in  this  disease 
and  is  indicated  in  obstinate  cases.  The  technique  is  frac- 
tional.   An  erythema  is  not  permissible. 

Acne  Varioliformis. — Fractional  doses  are  helpful  in 
this  affection. 

Sycosis. — Sycosis  vulgaris  (staphylogenic  sycosis)  and 
sycosis  parasitica  (sycosis  barbae;  ringworm  sycosis).  In 
the  bacterial  type  it  is  surprising  how  promptly  a  long- 


480  U.  S.  ARMY  X-RAY  IMANUAL 

standing  case  will  respond  to  a  few  fractional  treatments. 
At  times,  however,  it  is  necessary  to  effect  a  defluvinm  of 
the  affected  area.  Relapses  are  common.  X-ray  treatment 
is  equally  efficacious  in  the  parasitic  type  excepting  that 
here  it  is  always  necessary  to  effect  epilation. 

Technique. — Parasitic  sycosis  usually  exists  as  one  or 
several  isolated,  well-defined  areas.  Apply  a  single  epilat- 
ing  dose  (H  1)  to  each  area.  Sycosis  vulgaris  is  likely  to 
involve  the  entire  bearded  region  and  the  upper  lip.  Ap- 
ply fractional  doses  in  the  following  manner:  Place  the 
anode  over  mandible  of  both  jaws  and  over  the  point  of  the 
chin  with  the  head  extended.  Each  treatment  is  at  right 
angles  to  the  others  and  the  anode  is  always  the  same  dis- 
tance from  the  skin.  Protect  the  mucous  surfaces  of  the 
lips,  the  nose,  eyes,  eyebrows,  and  scalp.  Apply  H  i/4 
every  five  days  until  H  1  has  been  given  and  then  stop. 
The  hair  should  fall  out,  without  erythema,  a  week  or  two 
later.  If  the  lesions  begin  to  disappear  after  the  first 
or  second  treatment  it  may  not  be  necessary  to  administer 
further  treatment. 

Caution. — Avoid  use  of  sulphur,  mercury,  etc.,  before, 
during,  and  after  x-ray  treatment. 

Favus. — If  this  contagious  disease  should  gain  headway 
in  the  army  it  would  be  necessary  to  treat  each  individual 
head  with  the  x-ray.  There  is  no  other  satisfactory  treat- 
ment and,  with  a  reliable  technique,  the  result  is  certain. 

Technique. — The  method  of  applying  the  x-ray  to  favus 
and  ringworm  of  the  hairy  scalp  is  known  as  the  Kien- 
bock-Adamson  method.  It  consists  of  dividing  the  scalp 
into  five  areas  and  administering  an  epilating  dose  (HI; 
spark-gap  7  to  9  inches)  to  each  area  at  one  sitting.  The 
face,  ears,  neck  and  back  are  shielded.  The  anode  must  be 
always  at  the  same  distance  and  each  treatment  at  right 
angles  to  every  other  treatment.    The  scalp  is  marked  out 


CUTANEOUS  X-RAY  THERAPY  481 

in  the  following  manner :  First,  the  hair  is  clipped  close 
to  the  scalp.  A  mark  is  made  in  the  middle  line  one  inch 
inside  the  anterior  hair  line.  xV  similar  mark  is  made  one 
inch  inside  of  the  posterior  hair  line.  These  marks  should 
be  exactly  10  inches  apart.  If  not,  they  are  adjusted  so 
that  the  required  distance  is  obtained.  Then  a  mark  is 
made  exactly  in  the  center  of  this  line.  Two  more  marks 
are  made  about  one  inch  above  and  a  trifle  forward  of  the 
external  auditory  meatus.  These  marks  are  so  adjusted 
that  they  are  exactly  5  inches  from  every  other  mark.  The 
requirements  are : 

1.  Five  inches  between  each  mark. 

2.  Each  treatment  exactly  at  right  angles  to  every  other 
treatment. 

3.  Maintain  constant  anode-skin  distance. 

4.  Accurate  measurement  of  epilating  dose. 

5.  Shield  face,  ears,  neck  and  back. 

6.  Direct  beam  must  strike  each  one  of  the  five  marks. 

7.  Allow  incident  rays  to  overlap. 

8.  Avoid  irritating  chemicals  before  and  after  treat- 
ment. 

9.  Remove  crusts  before  applying  the  x-ray. 

10.  The  head  must  be  stationary. 

11.  Eight  inches  is  a  good  working  distance. 

The  hair  will  fall  out  three  weeks  subsequent  to  the 
treatment  and  will  begin  to  regrow  in  from  one  to  three 
months.  It  is  not  necessary  that  all  the  hair  fall  out;  if 
most  of  it  falls  out  the  end  result  is  satisfactory.  There 
should  not  be  an  erythema.  A  transitory  erythema  (last- 
ing a  day  or  two)  need  occasion  no  alarm.  A  severe  reac- 
tion is  likely  to  cause  permanent  alopecia.  Fractional  treat- 
ment will  accomplish  the  same  result  providing  a  total  of 
H  1  is  administered  in  three  weeks.     The  accompanying 


482 


U.  S.  ARMY  X-RAY  IMANUAL 


n3 

o 

a 

o 

s 

M 


c3 


O 


i 

(73 


00 
rH 
(M 

n3 
03 

CM 


CUTANEOUS  X-RAY  THERAPY 


483 


illustrations,  Figs.  217  to  219,  explain  better  than  words 
the  location  of  the  points  or  marks,  the  overlapping  of  the 


Fig.  219.     After  depilation  by  Aclamson  method. 


rays,  the  direction  of  the  central  ray,  the  angles  at  which 
the  treatments  are  given,  etc.  The  lines  between  the  five 
points  aid  in  determining  the  angle  for  the  treatments. 


484  U.  S.  ARI\IY  X-RAY  ]\IANUAL 

Onychomycosis  (Ringworm  of  the  Nails).— Sometimes 
this  ait'ectioii  yields  readily  to  x-ray  treatment.  At  other 
times  it  is  extremely  obstinate  and,  frequently,  it  will  not 
respond  at  all. 

Technique. — Shield  close;  fractional,  semi-intensive  or  in- 
tensive. 

Actinomycosis  and  Blastomycosis.— These  diseases  usu- 
ally involute  rapidly  under  both  fractional  and  intensive 
treatments ;  occasionally  they  do  not. 

Hyperidrosis. — Excessive  sweating  of  the  palms  and 
soles  can  be  cured  by  radiotherapy. 

Tech7iique. — Fractional  or  intensive,  preferably  the  lat- 
ter. H  %  to  H  1  every  four  weeks  for  from  two  to  six 
treatments.  If,  after  the  second  exposure,  sweating  is 
markedly  reduced,  discontinue  the  treatment.  Do  not  cause 
complete  cessation  of  perspiration,  as  skin  will  become  too 
harsh  and  dry.  In  treating  the  palms  it  is  possible  to 
slightly  flex  the  fingers  and  thumb  so  that  all  parts  will 
receive  an  equal  dose  (in  accordance  with  inverse  square 
of  distance).  Pirie  has  devised  a  convex  celluloid  support 
for  the  hands  which  is  a  great  aid  in  treating  the  palms,  as 
the  convexity  is  so  arranged  that,  when  the  direct  beam  is 
centered,  every  part  of  the  flexor  surface  of  the  palms, 
fingers  and  thumbs  will  receive  the  same  amount  of  ray. 

Pruritus. — Idiopathic  pruritus  ani  will  usually  yield  to 
fractional  doses.    The  relief  is  temporary. 

Chronic  Ulcers  and  Indolent  Wounds. — Indolent 
wounds  and  ulcers  may  at  times  be  stimulated  and  benefited 
by  fractional  treatment.  This  is  true  of  some  examples  of 
ecthyma,  ulcers  from  insect  bites,  gun-shot  wounds,  vari- 
cose ulcers,  etc.  It  is  probable  that  better  results  might 
be  obtained  by  means  of  heliotherapy  or  phototherapy. 


SYNOPTICAL  TABLE   OF   CONTEXTS 
AND   INDEX 


SYNOPTICAL  TABLE  OF  CONTENTS 


X-RAY  PHYSICS 

X-RAYS  AND  Electricity 

Introduction,  15 
X-rays,  15 
Paths,  17 
Velocity,  17 
Energy,  17 
Scattering,  17 
Passage  through  matter,  18 
Electrons,  18 
Production  of  x-rays,  19 
General    instructions   and   pre- 
cautions, 20 
Electrical  terms,  22 

Charges,  22 

Generators,   22 

Voltage,  23 

The  volt,  23 

Current,   23 

The  ampere,  23 

Eesistance,  23 

The  ohm,  24 

Power,  24 

The  watt,  24 

Derived  units,  24 
Measuring  instruments,  25 
Electric  circuit,  25 
Direct  current   (d.c.)j  26 
Alternating   current    (a.c),   27 
X-ray    current-voltage    require- 
ments, 27 
High  voltage,   27 

Tubes  and  X-ray  Production 

The  gas  tube,  29 
The  Coolidge  tube,  31    • 
No  inverse,  35 
Penetration  limits,  35 
No   fluorescence    in    the    glass, 
35 


New  form  of  Coolidge  tube,  36 
Tube  focus,  38 
Conditions  for  operation,  39 
Gas  tube  characteristics,  41 
Danger  in  testing,  42 
Coolidge    tube    characteristics, 

42 
Outflow  of  radiation,  43 
Amount  of  radiation,  44 
Quality,  44 
Dependence     of     quantity     on 

electrical  conditions,  45 
Penetration,  46 

X-RAY  Machines 

X-ray  transformer,  47 
Control  of  the  transformer,  48 
Eheostat,  49 
Autotransformer,  52 
Inductance  taps,  56 
Transformer  chart,  57 
How  to  use  the  chart,  58 
Synchronous  motors,  60 

Starting,  60 
Polarity   indicator,    60 
Eotary  converter,  62 
Eectifier,  64 
Sparking  troubles,  66 
Noise,  6Q 
Inverse,  66 

Electromagnet  and  solenoid,  67 
Choke  coil,  68 
Protection  against  surge,  68 
Eemote  control  switch,  69 
Line  wiring,    70 
High  tension  wiring,  72 

Care  of  Apparatus 

Tracing  circuits,  75 

Locating  trouble,  78 
Primary  circuit,  80 
Secondary  circuit,  81 


487 


488 


SYNOPTICAL  TABLE  OF  CONTENTS 


Care  of  tubes,  82 
Care  of  motors,  84 
Care  of  transformers,  85 
Care  of  batteries,  86 
Emergency  provisions,  89 
Polarity  indicator,  89 
Milliammeter,  90 
Timer,  90 
Eemote  control,  91 
Protective   resistance,   91 
Motor  or  rectifier,  91 
Autotransformer  or  rheostat, 

92 
Fuses,  93 
Ordering  supplies  and  repairs, 
94 

Induction  Coils 

Coil  characteristics,  95 
Valve  tubes,  96 
Interrupters,  98 
The  Wehnelt  interrupter,  99 

Operating  notes,  99 
The   mercury   interrupter,    100 

Operating  notes,  101 
Tubes  for  use  with  coils,  102 
Headings,  104 
Portable  coils,  104 

Photographic  and  Dark  Koom 
Work 

Fast  work,  104 

Photographic  density  and  char- 
acter of  negative,  105 
Exposure  table,  108 
Plates  and  films,  110 
Filling  envelopes  and  cassettes, 

111 
Intensifying  screens,  112 
Care  in  handling  plates,  113 
Tank  development,  116 
Temperature,  116 
Concentration,  116 
Plate  defects,  116 
Examining  negatives,  117 
Developer  action,  117 
* '  Hypo ' '  or  fixing,  119 
Fog,  119 

Developing  formulae,  120 
Hydrochinone,  120 


Elon-hydroehinone,  120 
Edinol-hydrochinone,    121 
Metabisulphite-hydrochinone, 
121 

Fixing  bath  formula,  122 

Chrome  alum  fixing  Ijath,  122 

Notes  on  fixing,  122 

Eeducing  dense  negatives,  123 

Darkroom,  123 
Arrangement,  124 
Ventilation,  125 
Humidity,  127 

Care  of  utensils,  127 

Supplies,  127 

Marking  negatives,  127 

The  x-ray  negative,  128 

Eecords,  132 

LABORATORY 
EXPERIMENTS 

Laboratory  instruction  in  prep- 
aration for  Roentgenology, 
133 
Instruction  unit,  134 
Test  plates,   136 

Distance-time    relation,    test 

plate  No.  1,  138 
Distance-time    relation,    test 

plate  No.  2,  139 
Voltage-time     relation,     test 

plate  No.  3,  140 
Summary    of    the    preceding 
relations,  test  plate  No. 
4,  141 
Change  in  time  of  exposure 
with        thickness,        test 
plates  Nos.  5  and  6,  144 
The     Benoist     penetrometer, 
test  plate  No.  7,  146 

NEW  APPARATUS 

Army  x-ray  table,  150 

Setting   up    table    (portable, 

158 
Cautions,  159 

Some  operating  points,  160 
List  of  numbers  referring  to 

illustrations    of     standard 

tables,  162 


SYNOPTICAL  TABLE  OF  CONTENTS 


489 


Fluoroscopic  room  illumina- 
tion, 1G3 

To  find  target-screen  dis- 
tance, 163 

Examples,  i64 

Centering  tube  in  the  box  be- 
neath the  table,  165 

The    U.    S.    Army    portable 
x-ray  unit,  167 

Engine,  169 

The  transformer  unit,  171 

Eed    light    for    fluoroscopic 

room,  177 
Limitations,  177 

The  U.  S.  Army  bedside  x-ray 

UNIT,  179 

Limitation    of   tube   current, 

179 
Service  conditions,  180 
Operation,    180 
X-ray  transformer,  183 
Tube,    184 

To  adjust  the  tube,  184 
Care  in  moving,  185 
Exposure,  185 
Accessory  apparatus,  186 

Fluoroscopic  unit,  187 

STANDARD  POSITIONS 

Standard  positions,  188 

DANGERS  AND  PROTECTION 

Dangers  from  the  x-ray,  194 
Protection     of     the     operator 

from  the  x-rays,  195 
Electrical  dangers,  198 
Type  of  control,  199 
Eesuscitation      from      electric 

shock  or  asphyxiation,  200 

FLUOROSCOPY 

Definition,  202 

Apparatus,   202 

Operating  switch,  204 

The    darkroom,    importance   of 

absolute  darkness,  204 
Ventilation  of  the  fluoroscopic 

room,  205 


Time    required    for    sensitizing 

the  retina,  205 
The    light    for    the    darkroom, 

205 
Conditions  for  fluoroscopy,  205 

LOCALIZATION 

General  considerations,  209 

Care  in  marking  and  recording, 

210 
Reports,  211 

Standard  Methods,  212 

Definitions,  218 
Central   ray,   218 
Vertical  ray,  218 
Method  A,  219 

Operating     instructions     for 
Method  A,  223 
Method  B,  224 
Apparatus,  227 
Operation  of  Method  B,  229 
Simpler  method  of  operation, 
230 
Method  C,  230 

Specific       instructions       for 
Method  C,  236 
Method  D,  238 

Specific       instructions       for 
Method  D,  240 
Method  E,  241 

Fluoroscopic  method,  vrith  aux- 
iliary compass,  250 
Setting    the    Hirtz    compass, 

252 
Direct   setting   of   the    Hirtz 

compass,  255 
Use   of   Hirtz   compass  with 
plates,  261 
Method  F,  267 
Fluoroscopic   assistance   during 

operation,  272 
Depth  of  anatomical  landmarks 
beneath  the  skin,  275 

Eye  Localization,  278 

First  exposure,  282 
Second  exposure,  284 
Charting  the  plates,  288 


490 


SYNOPTICAL  TABLE  OF  CONTENTS 


BONES  AND  JOINTS 

Fractures,  292 

Fluoroscopic  method,  293 
Plate  method,  293 
Location  of  tube,  295 
Position  for  exposure,  297 
Eadiographs      made      through 

splints  or  casts,  297 
The  appearance  of  callus,  298 
Reports,  299 
Negative  reports,  300 
X-ray  osteology,  300 
Epiphyses,  300 
Plate  defects,  301 
Conclusions  to  be  drawn  from 

plates  influencing  methods 

of  re-position,  301 
Setting  of  fractures  under  the 

fluoroscope,  301 
Radiographs    with    patient    in 

bed,  302 

Dislocations,  303 

Reduction  of  dislocations  with 
fluoroscopic  aid,  303 

Fluoroscopy  vs.  radiography, 
304 

Fracture  of  the  Skull,  304 
Frontal  region,  306 
Temporoparietal,    308 
Posterior  region,  309 
Base  region,  310 

Examination  of  Spine,  312 

Upper  cervicals,  316 
Lower  cervicals,  318 
Thoracic  vertebrae,  320 
Upper  lumbar  region,  320 
Abnormalities  of  the  spine,  322 
Spinal  joint  lesions,  325 
Spinal    transitional    lesions, 

325 
Spinal  bone  lesions,  326 

Lesions  of  the  Long  Bones,  327 
Point  of  origin,  328 
Bone  production,  328 
Cortex,  329 
Invasion,  330 


Special  Lesions,  331 
Carcinoma,    331 
Round-cell  sarcoma,  331 
Spindle-cell  sarcoma,  331 
Periosteal  sarcoma,  332 
Osteosarcoma,  332 
Giant-cell  sarcoma,  333 
Enchondroma,    333 
Cyst,  333 
Osteoma,  334 

Ossifying  hematomata,  334 
Osteitis  fibrosa  cystica,  335 
Paget 's  disease,  335 
Brain  tumors,  336 
Osteomyelitis,  336 
Periostitis,  337 

Arthritis,  339 

Infectious  arthritis,  340 
Atrophic  arthritis,  341 
Hypertrophic   arthritis,  342 
Tuberculosis  of  the  joint,  343 
Gonorrheal  arthritis,  344 
Syphilitic  arthritis,  344 
Charcot  joint,  345 

SINUSES  AND  MASTOIDS 

Technique  for  mastoids,  346 

Technique  for  accessory  sin- 
uses,  348 

Interpretation  of  mastoid 
plates,  353 

Interpretation  of  accessory 
sinuses,  355 

TEETH  AND  MAXILL.G 

Placing  the  film,  357 
Exposure,  365 
Interpretation,  365 

THORACIC  VISCERA 

Methods  of  examination,  369 
Chest 

Types    of    x-ray    chest   plates, 

373 
The    normal    lung,    374 
Pulmonary  tuberculosis,   377 
Relation  of  the  x-ray  to  the 
clinical  examination,  377 


SYNOPTICAL  TABLE  OF  CONTENTS 


491 


X-ray  evidence  of  early  tu- 
berculosis,  378 
Advanced   tuberculosis,    379 
Progress  of  the  lesion,  380 
Tuberculous  cavities,  381 
Miliary  tuberculosis,   382 
Activity,  383 
Pneumonia,  384 
Diseases  of  the  pleura,  385 
Pleurisy,  385 
Pleural  effusions*  385 
Pneumothorax  and  hydro  or 
pyopneumothorax,  387 
The  diaphragm,  389 
Lung  abscess  and  bronchiecta- 
sis, 390 
Abscess  cavities,  392 
Differential  diagnosis,  395 
New  growths  of  the  lungs,  396 
Metastatic  new  growths,  396 
Primary  new  growths,  396 
Mediastinal     new      growths, 
397 
Heart 

Aneurysm      of      the      thoracic 

aorta,  399 
X-ray      examination      of      the 
heart,  402 
Normal     variations     of     the 

heart  shadow,  404 
Heart  size,  404 
Dilatation    and    hypertrophy 

of  the  heart,  405 
Displacement    of    the    heart, 

406 
Valvular  lesions,  407 
Nephritis  and  arterial  hyper- 
tension, 407 
Angina    pectoris    and    angi- 

noid  pains,  408 
So-called     functional     heart 

disease,  409 
Heart  function,   410 
Pericarditis,  411 
Method  of  heart  measurement, 
412 

URINARY   TRACT 

Preparation     of     the     patient, 
419 


Technique,  420 

Quality  of  tube,  425 

Position,  425 

Quality  of  the  plate,  426 

Pyelography,  427 

Demonstration  of  calculi,  428 

Sources  of  error  in   diagnosis, 

430 
Use  of  opaque  catheter,  433 

GASTRO-INTESTINAL 
TRACT 

Preparation  of  the  patient, 
435 

Method  of  examination,  437 

The  esophagus,  438 

Stomach,  441 

Small  intestine,  445 

Colon,  449 

Lower  right  quadrant  (ap- 
pendix, cecum  and  ileum), 
456 

Gall-bladder,  461 

MEASUREMENT    OF   X-RAY 
DOSE 

Measurement  of  x-ray  dose, 
463 

CUTANEOUS    X-RAY 
THERAPY 

Protection  to  patients,  469 
Eadiodermatitis,  469 
Biology,  472 

Diseases  and  Conditions 

Eczema,  472 

Psoriasis,  473 

Dermatitis  exfoliativa,  474 

Lichen  planus,  474 

Lichen    chronicus    circumscrip- 

tus      and      lichenification, 

475 
Pompholyx  (dysidrosis),  475 
Clavus,   calositas,  verrucee,  475 
Keloids,      hypertrophic      scars, 

cicatricial  tissue,  etc.,  475 
Plastic  surgery,  476 


492         SYNOPTICAL  TABLE  OF  CONTENTS 

Tuberculosis,  477  Onychomycosis     (ringworm    of 

Epithelioma,  478  the  nails),  484 

Sarcoma,  479  Actinomycosis     and    blastomy- 

Mycosis  fungoides,  479  cosis,  484 

Acne  vulgaris,  479  Hyperidrosis,  484 

Acne  varioliformis,  479  Pruritus,  484 

Sycosis,  479  Chronic     ulcers     and     indolent 

Favus,  480  wounds,  484 


INDEX 


Abnormalities  of  the  spine,  320 
Abscess,  acute,  of  incisors,  362 
multiple   chronic   apical,   363 
of    lung    and   bronchiectasis, 
390 
Abscess    cavities    in     the     lung, 
392 

position  for  examination  of, 
393 
Abscesses  of  unerupted  teeth,  366 
Accessory   sinuses,   plates  of,  in- 
terpretation, 355 

position  of  for  examination, 

351 
technique  of  examination  of, 
348 
Accommodation   of   the   eyes  for 

fluoroscopy,  205 
Achylia  gastrica,  435 
Acne,  types  and  x-ray  treatment 

of,   479 
Actinomycosis,     x-ray    treatment 

of,  484 
Adhesions  of  gall-bladder,  461 
in    the    lung,    location    and 

character  of,  388 
intestinal,  449 

where   commonly  found, 
456 
Air-cooled  Coolidge  tube,  36 
Alopecia,  470 
Alpha  rays,    17 
Alternation,  27 
Alternating  current,  27 
Alum  fixing  bath,  122 
Aluminum   acetate,   use   in   x-ray 

dermititis,  471 
Alveolar    margin,    localized    area 

of  destruction  in,  361 
Ampere,  23 

493 


Anatomical  depths,  table  for  de- 
termination of,  276,  277,  278 
Anatomical  landmarks,  275 
Aneurysms  of  the  thoracic  aorta, 

399-402 
Angina     pectoris     and     anginoid 

pains,  408 
Angina  pectoris  in  the  young  and 
old,  cardiac  appearance  on  the 
screen  of,  409 
Angulation  in  the  jejunum,  449 
Ankle,  position  for  exposure  of, 

191 
Antrum,   348 

Aortic  aneurysm,  x-ray  in   diag- 
nosing, 399 

changes  produced  by  growth 

of,  402 
order  of  frequency  of,  400 
Aortic  aneurysm  and  mediastinal 
tumors,   differentiation  of,  401 
Aortic  insufficiency,  406,  407 
Apparatus  for  fluoroscopy,  202 
Apparatus,  new,  149 
Appendicitis,   chronic,  449 

reflex  spasm  in,  449 
Appendix,   vermiform,   456-461 
relation  of  to  the  cecum  and 
ileum,  457 
Army  bedside  unit,  302 
Arrangement  of  dark  room,  124 
Arterial   hypertension,    407 
Arthritis,  339 

acute  polyarticular,  339 
arthritis  deformans,  339 
atrophic,  341 
gonorrheal,  344 
hyperatrophic,  342 
infectious,  340 
syphilitic,  344 


494 


INDEX 


Atheroma  of  the  aorta,  408 
Atomic  weight  of  target  material, 

30 
Atonic  constipation,  456 
Atrophic  arthritis,  341 
Atrophy    produced   by   erythema, 

470 
Autotransformer,  52 

compared  with  rheostat,  55 
failure  of,  92 
Auxiliary  comjjass,  248 

Bandages,      radiographing 

through,  298 
Barium  sulphate  in  x-ray  diagno- 
sis,  434 
Base  hospital  table,  151 
Basilar  region  of  skull,  position 

for  examination,  311 
Batteries,  care  of,  86 
Bazin's  disease,  x-ray  treatment 

of,  478 
Bedside  x-ray  unit,  179 

accessory  apparatus,   186 

care  in  moving,  185 

exposure,  185 

limitation,  177 

operation  of,  180 

service  conditions,   180 

tube  adjustment,  184 

use  at  the  bedside,  302 

x-ray  transformer,  183 
Benign  strictures  of  the  esopha- 
gus, 438 
Benoist  penetrometer,  146 
Beta  rays,  17 
Biological    action    of    the    x-ray, 

472 
Blastomycosis,    x-ray    treatment 

of,  484 
Bone  lesions,  326 
Bone  tumors,  327 

bone  production  in,  328 

cortex  of,  329 

point  of  origin  of,  328 

summary  of,  338 
Brain  tumors,  336 
Breast,  carcinomata  of,  330 
Broadbent's  sign,  412 
Bronchial  carcinoma,  397 


Bronchial   nodes   and   hilum,    tu- 
berculosis of,  382 
Bronchiectasis,  390 
Brushes,  trouble  with,  84 

Calcifications  of  portions  of  the 

ureter,  433 
Calculi,    demonstration    of,    428, 
429. 
of  the  gall-bladder,  461 
Calculus,  x-ray  in  disclosing  pres- 
ence and  nature  of,  419 
Callositas,    radiotherapy    in,    475 
Callus,  appearance  of,  298 
Calomel,    in    preparation    of    pa- 
tients, 419 
Cannula  and  trochar,  267 
Carcinoma,  331 

metastasis  in,  330 

of  the  colon,  449,  452,  453 

of  the  esophagus,  439 

of  the  lung,  397 

of  the  stomach,  447 

location    and    indication 
of,  445 
prostatic,  332 
Cardiac  lesion,  characteristic  sil- 
houette of,  407 
Cardiospasm,  438,  440 
Cardiovascular  shadow^  curves  of, 

402 
Cassettes,  111 
Casts,      radiographing      througli, 

297 
Catheter,  opaque,  433 
Cavities  in  the  lung,  391-396 
Cecum,  dilatation  of,  456 
Centering  tube  in  box,  165 
Central  ray,  218 
Cervicals,  examination  of,  316 
Characteristics,     Coolidge     tube, 

42 
Characteristics,  gas  tube,  41 

of  induction  coils,  95 
Charcot  joint,  345 
Charges,  22 

Chart,  transformer,  57 
Chart,  use  of  transformer,  58 
Charting    eye    localization    data, 
288 


INDEX 


495 


Chemicals  enhancing  influence  of 
the  ray  in  therapy,  471 

Chest  plates,  variation   in  types, 
373 

Choke  coil,  68 

Chrome  alum  fixing  bath,  122 

Chronic  appendicitis,  reflex 
spasm,   449 

Chronic   ulcers,    fractional   treat- 
ment in,  484 

Cicatricial  tissue,  x-ray  treatment 
of,  475 

Cicatrization   in   hourglass   stom- 
ach, 443 

Circuit,  electric,  25 

Circuits,  diagrams  of,  76,  77,  79 

Circuits,  tracing  of,  75 

Clavicle,    position    for    exposure, 
188 

Clavus,  x-ray  treatment  of,  475 

Coil,  induction,  95 

Colitis,  mucous,  449 

Colon,     pathological     conditions, 
449-456 

Colon,    conditions    of    for    x-ray 
study,  449 

Comminuted   fractures,   value    of 
stereoscopic  plates  in,  295 

Commutators,  care  of,  84 

Concentration  of  developer,  116 

Constipation,  functional,  456 

Contactors,  69 

Contrast,  108,  130 

Control,  relative  dangers  of,  199 

Control  of  transformer,  48 

Control   switch,   remote,   69 

Converter,  rotary,  62,  64 

Coolidge  filament  wiring,  73 

Coolidge  tube,  32 

characteristics  of,  42 
no  fluoroscence  in,  35 
no  inverse,  35 
penetration  limits,  35 
radiator  type,  36 
saturation  curve,  43 

Corns,  x-ray  treatment  of,  475 

Corona  loss,  74 

Cortex,   determining  presence  of, 
329 

Coulomb,  23 


Current,   alternating,   27 
direct,  26 
electric,  23 

relation  between  primary  and 
secondary,   49 
Current-time  relation,   140 
Cycle,  27 

Cystoscopy    in    locating    calculi, 
429 

Dangers,  electrical,   198 
Dangers  from  x-rays,  194 
Darkness,    importance   in   fluoro- 
scopy, 204 
Dark  room,  123 

arrangement,  124 
essentials,  123 
humidity,  127 
lighting,   123 
record   system,   127 
supplies,    127 
ventilation,  125,  126 
Defluvium  of  scalp  hair,  469 
Density  of  negative,  105 
Dental    films,    exposure    and    in- 
terpretation, 365 
Dental  films,  placing  of,  357,  365 
Dermatitis   exfoliativa,   474 
Detail,  108 

Developer   concentration,    116 
Developer,  temperature  of,  116 
Developers,  action  of,  117 
hydrochinone,  120 

edinol-hydrochinone,  121 
elon-hydrochinone,  120 
metabisulphite-hydrochi- 
none,   121 
Developing    formulae,     120,    121, 

122,  123 
Developing  tank,  116 
Diagram  of  circuits,  76,  77,  79 
Diagnosis,  differential  in  thoracic 
conditions,  395 

in  urinary  tract  examination, 
430 
Diagnostic  plate,   conditions  for, 

129 
Diaphragm,   movement   of,  390 
position  an  indication  of  dis- 
ease, 389 


496 


INDEX 


Diaphragm,    variation    in    shape 
and  position,  389 

Differential  diagnosis  in  thoracic 
conditions,  395 

Dilatation    and    hypertrophy    of 
the  heart,  405 

Dilatation,   in  malignant  intesti- 
nal growths,  438,  440 
of  gall-bladder,  462 
of  stomach,  444 

Direct  current,  26 

Dislocations,     determination     of, 
303 

reduction  under   fluoroscopic 
aid,  303 

Displacement  of  the  heart,  406 

Distance,  target  screen,  163 

Distance-time  relation,  139  - 

Diverticulitis,  449 

Diverticulum,  438 

Dorsoventral  position,  advantage 
of  in  aortic  aneurysm,  399 

Dosage  equivalents,  table,  468 

Dosage,  measurement  of,  463 

Dressings,      radiographing 
through,   298 

Drop  heart,  410 

Duodenal  bulb,  deformity  of,  446, 
448 

Duodenal  ulcer,  448 

Duodenum,  dilatation  of  in  adhe- 
sions, 456 

Duodenum,  ulcer  in,  44G,  448 

Dyschezia,  456 

Eczema,  technique  of  x-ray  treat- 
ment of,  473 

x-ray  treatment  of,  472 
Edinol-hydrochinone       developer, 

121 
Elbow,  position  for  exposure,  189 
Electric  circuit,  25 
Electric    circuit,    Ohm's   law    of, 

26 
Electrical   dangers,   198 
Electrical   erythema,  470 
Electro-magnet,  67 
Electrons,  18 

high  speed  of,  20 

properties  of,  19 


Elon-hydrochinonc  developer,  120 
Emergency   provisions,    89 
p]mpyema,  postpneumonic,  384 
Enchondroma,  333 
Enemata    in    preparation    for    x- 

ray  examination,  434,  435 
Energy  of  x-rays,  17 
Engine,  portable  x-ray  unit,  169 
Enlargement  of  the  heart,  405 
Envelopes,  filling,  111 
Epilating  dose,  469 
Epiphysis,  300 

Epithelioma,  technique  in  x-ray 
treatment  of,  478 

types  of,  478 
Equal  density,  exposure  for,  142 
Erythema  dose,  195,  464,  469 
Esophagus,  benign  strictures  of, 
438 

carcinoma  of,  439 

cardiospasm    and    dilatation 
of,  438,  440 

lesions  of  the,  438 

malignant  growths  of,  438 

preparation    of    patient    for 
examination  of,  435 
Ethmoid  cells,  356 
Excessive  dosage  cause  of  radio- 
dermatitis,    470 
Excessive  exposure,  20 
Exostoses,  325 
Experiments,  laboratory,  purpose 

of,    133 
Exposure,  effect  of,  106 

excessive,  20 

for  dental  films,  365 

photographic      measure      of, 
137 

table,    108-109, 
Exposures,  bedside  unit,  185 

short,  conditions  for,  105 
Eye  localization,  278 

charting,  288 

Fan  ventilating,   126 

Eavus,  technique  of  x-ray  treat- 
ment for,  480 

Filament  current  transformer, 
34 

Filling  defects,  449    . 


INDEX 


497 


Film,   double   coated,    111 
Films,  care  in  handling,  113 
Films,  photographic,   110 
Filtration,  469 
Filtration  of  beam,  148 
Finzi  ink  formula,   211 
Fixation   in   gastro -intestinal  ad- 
hesions, 456 
Fixing  bath  formulae,  122 
Fixing,  notes  on,  122 
Fixing   solution,   119 
Flash  exposures,  83 
Fluorescence,    none    in    Coolidge 

tube,  35 
Fluoroscope,  disadvantage  in  di- 
agnosing   incipient    pulmonary 
tuberculosis  Avith,  378 
Fluoroscope,    reducing    fractures 

under  the,  301 
Fluoroscopic    room    illumination, 

163 
Fluoroscopic   room,  lighting  the, 

177 
Fluoroscopic  unit,  187 
Fluoroscopy,  202 

advantage  of  in  heart  exam- 

tions,  402 
conditions  for,    205 
in    examination    of    the    uri- 
nary tract,  420 
in  fractures  and  dislocations, 

304 
in  study  of  the  thoracic  vis- 
cera, 369 
time  limit  for,  195 
Focal  spot,  size  of,  38 
Fog  on  plates,   119 
Foot,  position  for  exposure,   192 
Formulae  for  developing,  120-123 
Fractional     treatment     of     skin, 

469 
Fracture  of  the  skull,  304 
Fracture    plates,    importance    of 

labeling,  294 
Fractures,  classified,  292 

comminuted,  value  of  stereo- 
scopic plates  in,  295 
fluoroscope  in,  301 
fluoroscopic     method     of 
studying,   293-294 


Fractures,  fluoroscopy  v.  radiog- 
raphy in  determining,  304 
negative  reports  ot,  300 
plate    methods    of    studying, 

293 
reports  of,  299 
transverse,  299 
Frontal   region,   position   for   ex- 
amination of,  307 
Frontal   sinuses,  examination  of, 

355 
Fuses,  failure  of,  93 
testing,   80 

Gagging,  prevention  of  in  placing 

film  in  the  mouth,  357 
Gall-bladder,  adhesions  of,  461 
calculi  of,  461 
dilatation  of,  462 
lesions  of,  461 
Gamma  rays,  17 
Gas  tube,  29 

characteristics  of,  41 
danger  in  testing,  42 
Gastric  hypermotility,  447 
Gastro-intestinal  tract,  abnormal 
and  pathological  variations  in, 
434 

method    of    x-ray    examina- 
tion of,  437 
technique  of  examination  of, 

434 
variations  in   evacuation   of, 
435,  436,  437 
Gastrojejunal  ulcers,  449 
Generators,  22 
Giant  cell  sarcoma,  333 
Gonorrheal  arthritis,  344 

Half  value  layer,  18 
Hampson  radiometer,  467 
Haustral  segment,   diminution  in 

size,  456 
Head  injuries,  stereoscopic  exam- 
ination in,  312 
Heart,  anginoid  pains  in,  409 

dilatation  of,  405 
Heart  and  arterial  conditions,  na- 
ture of  disclosed  by  the  x-rays, 
409 


498 


INDEX 


Heart,  decompensation,  406 
displacement    of,    406 
enlargement  of,  409 
functional      disturbance      of, 

due  to  over-strain,  410 
hypertrophy  of,  405 
in    emphysema   and    asthma, 

407 
in  nephritis  and  arterial  hy- 
pertension, 408 
in   thoracic   deformity,   407 
large  pericardial  elTusion  in, 

411 
normal  orthodiagram  of,  403 
x-ray  examination  of,  402 
Heart     disease,     congenital     en- 
largement in,  406 

so-called   functional,   409 
Heart  function,  410 

fluoroscopic   tests   barren   of 
results  in,  411 
Heart  lesions,  407 
Heart   measurement,   method   of, 
412 

position    for    radiographing, 
412 
Heart     shadows,     normal    varia- 
tions, 404 
Heart  size,  404 

tables  for  measuring,  414-416 
Hematomata,  ossifyinp-^  334 
Hemophilia,  345 
High  tension  wiring,  70 
Hilum  of  the  lung,  376 
Hilum  tuberculosis,  382 
Hip  joint,  position  for  exposure, 

190 
Hirtz  compass,  direct  setting  of, 
255 

fluoroscopic      method      with 

auxiliary,  250 
fundamental     principles     of, 

256 
plate  method,   261 
setting,  252 
table  for  setting,  266 
Holder  for  Hirtz  compass,  255 
Holzknecht    units    in    cutaneous 

x-ray  therapy,  469 
Hourglass,  organic,  443 


Humidity  of  dark  room,  127 
Hydrochinone    developer,    120 
Hydrogen  tube,  care  of,  82 
Hyperatrophic  arthritis,  342 
Hyperccmentosis,  361 
Hyperidrosis,  technique  of  x-ray 

treatment   of,    484 
Hypermotility,  gastric,  447 
Hyperperistalsis,  gastric,  447 
Hypersusceptibility^         acquired, 

471 
Hypertrophic    scars,   x-ray   treat- 
ment of,  475 
Hypertrophy  of  the  heart,  405 
Hypo  bath,  119 

Idiosyncrasy    in    radiodermatitis. 

471 
Ileal  stasis,  449 
Ileum,  abnormalities  in,  449 
Illumination,    fluoroscopic    room, 

163 
Immobilization       in       examining 

fractures,    294 
Incisors,  acute  abscess  of,  362 
Indicator,  polarity,  60 
Indolent    wounds,     fractional 

treatment  of,   484 
Inductance  taps,  56 
Induction  coil,  28,  95 
meter  readings,  104 
tube  for  use  with,  102 
Inertia    of    photographic    plate, 

106 
Infectious  arthritis,  340 
Ink,  skin  marking  formula,  211 
Instruction    unit,    description   of, 

134 
Instruments,     electrical     measur- 
ing, 25 
Insulation    of   transformer    coils, 

47 
Intensifying  screens,  112 
Intensive  treatment  of  skin,  469 
Intermittent  control,  273 
Interrupters,  98 
mercury,  100 
operating  notes  on,  101 
rotax,    101 
Wehnelt,  99 


INDEX 


499 


Intestinal  diverticula,  438 
obstruction,  447 
stasis,  449 
Inverse,   absence   of   in   Coolidge 
tube,  35 

wrong  setting  of  rectifier  re- 
sulting in,  66 
Inverse  square  law,  44,  138 

Jejunum,  lesions  in,  449 
Joint,  Charcot,  345 
Joint  lesions  of  the  spine,   325 
Joints,  tuberculosis  of,  338 
marked  hazing  in,  343 

Keloids,  x-ray  treatment  of,  475 

Keratoses,  470 

Kienbock  method,  dosage  meas- 
urement, 465 

Kienbock-Adamson  method  in 
treatment  of  favus,  480-483 

Kilovolt,    24 

Kilowatt,  24 

Kilowatt-hour,    24 

Kinks  and  adhesions,  449 

Knee,  position  for  exposure,  191 

Laboratory  experiments,  purpose 

of,  133 
Laminae,      congenital      non-union 

of,  323 
Landmarks   for   localization,   276 
Lesions* of  the  stomach,  443 
Lichen   chronicus   circumscriptus, 

475 
Lichen  planus,  technique  of  x-ray 

treatment,  474 
Lichenifications,   x-ray  treatment 

in,  475 
Light  for  fluoroscopic  room,  205 
Line  wiring,  70 
Lobar  carcinoma,  397 
Localization,  causes  of  error  in, 
214 

depth  methods  in,  216 

fluoroscopy  in,  247 

general      considerations      in, 

209 
in  lung  examination,  377 
surgical  guide  methods  in,  216 


Localization   apparatus,  essential 

features,  213 
Lumbar  examinations,  320 
Lumbar  vertebrae,  321 
Lumbosacral    region,    abnormali- 
ties, 323 
Lung,  abscess  cavities  in,  392 
adhesions  in,  387,  388 
evolution  of  abscess  in,  394 
hilum  of,  376 
normal,  374 
Lung  abscess  and  bronchiectasis, 

390 
Lung  cavities,  evidence  of  tuber- 
cular involvement,  381 

progressive  changes  in,  394, 
395 
Lung  plate,  typical,  374 
Lung  suppuration,  common  causes 

of,  391 
Lungs,    carcinoma    and    sarcoma, 
396-399 

new  growths  of  the,  396 
Lupus    erythematosus,    technique 
and  caution  in  x-ray  treatment 
of,  477 
Lupus  vulgaris,   x-ray   treatment 
of,  477 

Magnet,  electro,  67 

Malignant  growths  in  the  esopha- 
gus, 438,  439 

Mandible,  adjustments  for  expo- 
sure, 367 

Mandible,  sarcoma  of,  362 

Marking  negatives,  127 

Marking  the  skin,  210 

Mastoid  examination,  position  of 
patient,  346,  347 

Mastoid  plates,  interpretation  of, 
353 

Mastoid,  technique  of  examina- 
tion, 346 

Maxillae,  contour  determining  an- 
gle of  exposure,  365 

Maxillary  antrum,  examination 
of,  356 

Measurement  of  x-ray  dose, 
463 

Measuring  instruments,   25 


500 


INDEX 


Mediastinal  new   growths   in   the 
lungs,  397 

Melting  point  of  target  material, 
30 

Mercury  interrupter,  100 
operating  notes  on,  101 

Metabisulphite   hydrochinone   de- 
veloper, 121 

Metastatic  .growths  in  the  lungs, 
396 

Meter    readings    with    induction* 
coil,  104 

"Method  A,  219 

Method  B,  224 

substitution       method       for, 
230 

Method  C,  230 

Method  D,  238 

Method  E,  241 

Method  r,  267 

Methods,     standard    localization, 
212 

Miliary  tuberculosis,  382 

Milliammeter,  position  in  circuit, 
74 
trouble  with,  90 

Milliampere,  24 

Mitral  insufficiency,  406 

Mitral  stenosis,  406 

Motor,  failure  of,  91 
synchronous,  60 

Motors,  care  of,  84 

Mucous  colitis,  449 

Mycosis    fungoids,    x-ray    treat- 
ment of,  479 

Nails,  ringworm,  484 
Negative,  character  of,  105 

x-ray,  128 
Negative    reports    of    fractures, 

300 
Negatives,    dense,    reduction    of, 
123 

examination  of,  117 
marking  of,  127 
Nephritis  and  arterial  hyperten- 
sion, 407 
Nephritis,  chronic,  heart  in,  406 
Neuritis,    symptoms    of,    due    to 
pressure,  322 


Oblique    positions,    advantage    in 
certain  eli(>st  structures,  373 

Oblique  radiation  for  metatarsal 
bones,  296 

Obstruction,  acute,  452 
intestinal,    447 
partial,  454 

Ohm,  24 

Ohm 's  law,  26 

Onychomycosis,    x-ray    treatment 
of,  484 

Opaque  meal  and  opaque  enema 
in  study  of  the  appendix,  461 

Operation  under  fluoroscopic  con- 
trol, 272 

Ordering   supplies,  94 

Orthodiagraphy  most  valuable  in 
heart  examination,  402 

Os  calcis,  position  for  exposure, 
192 

Oscillogram,  103 

Oscilloscope,  97 

Ossifying  hematomata,  334 

Osteitis  fibrosa  cystica,  335 

Osteology,  x-ray,  300 

Osteoma,  334 

Osteomyelitis,  327,  336 

Osteosarcoma,  332 

Paget 's  disease,  335 

Parallax  method,   224 

Parasitic   sycosis,   technique   and 

caution  in  x-ray  treatment,  480 
Pastille  in  measurement  of  dose, 

464 
Paths  of  x-rays,  17 
Patient,  position  of  for  exposure, 

297 
Penetrometer,  Benoist,  146 
Penetration    in    examination    of 

fractures,  294 

influence  of  tube-voltage  on, 

47 
of  radiation,  46 
Penetration    limits    of    Coolidge 

tube,  35 
Pericarditis,    increasing    size    of 

heart   shadow,  411 
Periosteal  changes,  298 
Periosteal  sarcoma,  332 


INDEX 


501 


Periostitis,   837 
Peristalsis,  modified,  443 
Peritonitis,  tuberculous  stasis  in, 

449 
Photographic  density,  105 
Photographic      measurement      of 

x-ray  dose,  465 
Planimeter,  417 

Plastic   surgery,   x-ray  in   prepa- 
ration for  operations,  476 
Plate   defects,   care  in   interpret- 
ing, 301 
Plate   quality  in  examination  of 

the  urinary  tract,  426 
Plates,  care  in  handling,  113 
defects  in,  116 
fogging  of,  119 
full     reading     by     clinician, 

301 
of   fractures,   importance   of 

labeling  of,  294 
photographic,  110 
test,    138 
Pleura,  diseases  of  the,  385 
Pleural  effusions,  385 

changes  in  chest  caused  by, 

386 
shadows  cast  by,  385 
Pleurisy,  diagnosis  of  dry,  385 
Pneumonia,   lobar,   384 

shadows     cast     by     various 
forms  of,  384 
Pneumothorax,    hydro    and    pyo, 
387 

artificial,   388 
Polarity  indicator,  60 

trouble  with,  89 
Polarity,  switch,  61 
Pompholyx,  fractional  treatment, 

475 
Portable     unit,     control     adjust- 
ment, 175 

limitations  of,  177 
Portable  unit  table,  151 
Portable  x-ray  unit,  167 
engine  for,  169 
transformer  for,   171 
Position     of    patient     in     radio- 
graphing, 297 
Positions  for  exposure,  188 


Posterior  region  of  skull,  exam- 
ination  of,   309 

Power,  electrical,  24 

Precautions,  20 

Priniaiy  circuit,  charactei  isti's 
of,  28 

Primary  new  growtlis  of  the 
lungs,  396 

Production   of   x-rays,   19 

Profondometer,    239 

Prostatic  carcinoma,  332 

Protection  against  surge,  68 

for   healthy   skin,   hair,   etc., 

469 
from  x-rays,   194,  195 
of    operator    against    radia- 
tion, 301 

Protective  resistance,  failure  of, 
91 

Pruritus,  484 

Psoriasis,  technique  of  x-ray 
treatment,   473 

Pulmonary  tuberculosis,  relation 
of  x-ray  to  clinical  examina- 
tion in,  377 

Pyelography  in  examination  of 
the  urinary  tract,  427 

Pylorus,  spasm  of,  443 

Pyopneumothorax,  387 

Pyorrhoea,  advanced,  364 

Quadrant,  lower  right,  456 
Quality  of  radiation,  44 
Quality  of  x-ray  in  therapy  for 

skin  diseases,  469 
Quantity,    photograjjhic    measure 

of,   137 

Eadiation,  electrical  conditions 
governing,  45 

measurement    of,    for    treat- 
ment, 463 
outflow  of,  43 
penetration  of,  46 
photographic  measure  of,  44 
quality  and  quantity,  44 
Radiator  type  of   Coolidge   tube, 

36 
Eadiodermatitis,  469 

acquired    hypersusceptibility. 
471 


502 


INDEX 


Eadiodermatitis,  degrees  of,  470 
etiology,  470 
reactions,  470 
sequelae,  470 
treatment  in,  471 
Kadiographing    patients    in    bed, 

302 
Eadiograpliy    in    examination    of 
the  urinary  tract,  420 

in  fractures  and  dislocations, 
304 
Radiometer,  Hampson,  467 

use    of    in    dosage    measure- 
ment, 465 
Eay,  central,  218 
vertical,   218 
Recording  localization  data,   210 
Records  of  x-ray  findings,  132 
Rectifier,  failure  of,  91 
high  tension,  64 
noise  of,  66 
setting  of,  66 
sparking  troubles,  66 
Rectum,  dilatation  of,  455 
Red  light  for  fluoroscopic  room, 

177 
Reducing  solution,  123 
Reference    numbers    to    illustra- 
tions of  x-ray  table,  162 
Reflex  spasm  in  chronic  appendi- 
citis, 449 
Regulation  of  transformer,  52 
Remote  control,  failure  of,  91 
Remote  control  switch,  69 
Repairs,  avoiding  delays,  94 
Report  form,  132 
Reports    of    localization    results, 

211 
Re-position,  problems  of,  301 
Resistance,  electrical,  23,  24 
Resuscitation  from  electric  shock, 

200 
Rheostat,  49 

compared      with      autotrans- 

former,  55 
failure  of,  92 
water  used  as  a,  93 
Rheostat    control,    disadvantages 

of,  51,  52 
Rheumatoid  affections,  340 


Ribs,  extra,  322 
Ringworm  of  the  nails,  484 
Rotary  converter,  62,  64 
Rotax  interrupter,  101 
Round-cell  sarcoma,  331 
Ruby  liglit,  124 

Rules  in  avoiding  unexpected  le- 
actions,  471 

Sacro-iliac  subluxation,  323 
Sandbags,  use  of  in  securing  mo- 
bilization, 294 
Sarcoid,  x-ray  treatment  of,  478 
Sarcoma,   329 

enchondroma,  333 
giant-cell,  333 
of  the  mandible,  362 
of  the  lung,  396,  397 
osteosarcoma,  332 
periosteal,  332 
round-cell,  331 
spindle-cell,  331 
types  of,  479 
Saturation  current,  34 
Saturation  curve,  Coolidge  tube, 

43 
Scattering,   17 

effect  of,  on  image,  146 
Sclerosis,   differentiating,  354 
cause     and     appearance     on 
plates,  354 
Scoliosis,  323 
Screen,  target,  163 
Screens,   intensifying,   112 
Secondaiy  circuit,  characteristics, 

28 
Selective  absorption,  147 
Self-rectifying  Coolidge  tube,  36 
Semi-intensive  treatment  of  skin, 

469 
Sensitizing  the  retina  for  fluoro- 
scopy, 205 
Shadows  in  lung  plates,  374,  375 
Shock,  resuscitation  from  electric, 

200 
Shoulder   joint,   position   for   ex- 
posure,  188 
Sinus,  positions  for  examination, 

349,  350 
Sinuses,  frontal,  356 


INDEX 


503 


Size  of  line  wire,  71 

Skin  marks,  210 

Skin,  toleration  dose,  469 

Skin  unit,  469 

Skull,  base  of,  310 

examination  of  base,  310 
examination    of    frontal    re- 
gion, 307 
fractures  of,  305 
frontal  region,  306 
posterior  region,  309 
temporoparietal  region,  308 
traumatic  injuries,  305 

Small  intestine,  lesion  in,  445 

Softening  devices,  31 

Solenoid,  67 

Spark  gap,  useless  with  self -rec- 
tifying tube,  37 

Spasm    of    the    esophagus,    438, 
440 

of  stomach,  443 

Spastic  constipation,  456 

Speed  in  exposure  of  plates,  con- 
ditions for,  105 

Speed     factor     of     intensifying 
screen,  112 

Sphenoid   sinus,  position  for  ex- 
amination, 353 

Spinal  abnormalities,  323 

Spinal  displacements,  315 

Spinal  examinations,  313 
lower  cervical,  317 
thoracic  vertebrae,  318 
upper  cervical,  316 
upper  lumbar   region,   319 

Spinal  fractures,  314 

Spinal   injuries,    fluoroscopic   ex- 
amination in,  312 

frequency  and  importance  of, 
312 

Spinal  lesions,  324 
bone,  326 
joint,  325 
transitional,  325 

Spinal      pathological      processes, 
modifications  of,  324 

Spindle-cell  sarcoma,  331 

Spine,  divisions  of,  314 

neuropathic  condition  of,  326 
pathological  changes  in,  324 


Splints,    radiographing    through, 

297 
Splints,    shadow    of   in    interpre- 
tation,  300 
Standard     army     bedside     unit, 

302 
Standard    methods    for    localiza- 
tion, 212 
list  of,  216 
Standard  positions,  188 
Stasis,  causes  of,  449 
Stasis  in  tuberculous  peritonitis, 

449 
Static  machine,  28 
Stereoscopic  plates,  in  comminut- 
ed fractures,  295 

in  pulmonary  lesions,  369 
Stereoscopy     in     extrapulmonary 

condition,  369 
Stomach,  carcinoma  of,  445,  447 
lesions  of,  443 
marked  dilatation  of,  444 
organic  hourglass  of,  443 
preparation    of    patient    for 

examination  of,  435 
spasm  of,  443 
ulcers  of,  441,  442,  443 
variations    in    size,    position, 
shape   and  motility   of,   441, 
442 
Storage  batteries,  care  of,  87 
Streptococcic  bronchopneumonias, 

384 
Strohl  method,  219 
Subgingival  abscess,  361 
Substances    producing    confusing 
shadows  in  urinary  tract  exam- 
inations, 431 
Sulci,  increase  in  depth  of  in  con- 
stipation, 456 
Supplies,  developing,  127 
Supplies,  ordering  of,  94 
Surface  leakage,     high     tension, 

74 
Surge,  protection  against,  68 
Sweet  method,  278 
Sycosis,  479 
Synchronous  motors,  60 

starting,  60 
Syphilitic  arthritis,  344 


504 


INDEX 


Table  of  exposures,  108,  109 

Table,  army  x-ray,  loO 

operating  jioints  for,  160 
precautions  in  use  of,  159 
setting  up,   158 
principal  parts  of,  150 

Tables  of 

anatomical   depths,   276-278 
developing  formula^,   120-123 
dosage  equivalent,  468 
exposure  time,  108-109,  139- 

141,   144-145 
heart  size,  414-416 
Hirtz  compass,  266 
wire  sizes,  71 

Tank  development,  116,  125 

Taps,  multiple  primary,  56 

Target  material,  30 

Target-screen  distance,  163 

Technique    of    radioscopic    exam- 
ination of  fractures,  294 

Teeth,     abscesses    of    unerupted, 
366 

advanced  pyorrhoea,  364 
alveolar  process,  360,  363 
and    maxillae,    interpretation 

of  films,  365 
exposures    and    adjustments, 

358-359,  366-368 
hypercementosis,  361 
multiple    chronic    apical    ab- 
scesses, 363 
normal,  360 
placing  of  dental  films,  357, 

365 
sarcoma  of  mandible,  362 
subgingival   abscess,   361 
unerupted  abscesses  of,  36C 

Telangiectasia,  470 

Temperature  of  developer,  116 

Temporoparietal    region,    exami- 
nation of,  308 

Tesla  coil,  104 

Test  lamp,  use  of,  80 

Test  plates,  138 

Testing  gas  tube,  42 

Thermionic    emission    of    metals, 
32 

Thickness,     effect     on     exposure 
time,  145 


Thoracic    vertebrae,    examination 

of,  318,  319 
Thoracic  viscera,  exposure   time, 
369 

method  of  examining,  369 

oblique  positions  in  examina- 
tion, 373 

positions     for     examination, 
370-373 
Timer,  failure  of,  90 
Trachea,  376 
Tracing  circuits,  75 
Transformer,  28 

for  bedside  unit,  183 

control  of,  48 

filament  current,  34 

high  tension,  47 

portable  x-ray  unit,  171 

protection      against      surge, 
47 

winding  ratio  of,  49 
Transformer  chart,  57 

use  of,  58 
Transformer  coils,  insulation  of, 

47 
Transformers,  care  of,  85 

closed   magnetic   circuits,    29 
Transitional  lesions,  325 
Traumatic  pathology,  description 
of  on  x-ray  plates  of  fractures, 
299 
Triangulation  method,  230 
Trochar  and  cannula,  267 
Trouble,  location  of,  78 

portable    unit    engine,     170, 
171 
Tube,  centering  in  tube  box,  165 

Coolidge,  32 

focus  of,  38 

gas,  29 

hydrogen,  82 

location  of,  295 

valve,  96 
Tubes,  care  of,  82 

conditions  for  operation,  39 

for  induction  coils,  102 

softening  devices,  31 

water  cooling  of,  31 
Tubercular  activity,  clinical  ver- 
sus x-ray  examination,  383 


INDEX 


505 


Tubercular   lesions,    progress   of, 

380 
Tuberculosis,  cutaneous  manifes- 
tations, 477 

diagnosis    of,    limitations   of 

the  x-ray  in,  377,  378 
incipient,  essentials  for  diag- 
nosis, 379 
x-ray  evidence  in,  378 
pulmonary, 

advanced,  379 
bronchial  nodes  and  hi- 

lum,  382 
miliary,    382 
progress  of  lesions,  380 
relation  of  x-ray  to  clin- 
ical examination,  377 
tuberculous  cavities,  381 
x-ray   evidence   in   early 
stages,  378 
Tuberculosis       orificialis,       x-ray 

treatment  of,  478 
Tuberculosis  verrucosa  cutis,  477 
Tuberculous  adenitis,  x-ray  treat- 
ment of,  478 
Tuberculous      bronchopneumonia, 

384 
Tuberculous   peritonitis,    extreme 

degree  of  stasis,  449 
Tumors  of  bone,  327 
Tumors  of  ribs  and  spine,  shad- 
ows    simulating     intrathoracic 
growths,  399 

Ulcer  of  the  duodenum,  448 
Ulcers,  chronic,  484 

of    the    stomach,    441,    442, 
443 
Unit,  bedside  x-ray,  179 
fluoroscopic,  187 
for    instruction,    description 

of,  134 
portable  x-ray,  167 
Units,  electric,  derived,  24 
Upper  jaw,  adjustments  for  ex- 
posure, 366,  368 
Ureter,  calcifications,  433 
Uric   acid   calculi  in   the  ureter, 
430 


Urinary  tract  examination,  cal- 
cifications of  portions  of  the 
ureter,  433 

conditions  to  be  demonstrat- 
ed by  pyelography,  428 

demonstration       of       calculi 
428,  429 

devices  to   prevent  intrusion 
of  the  abdominal  wall,  425 

difficulties  of  diagnosis,  430, 
431,  432 

interference  of  clothing  and 
bandages,  425 

list  of   substances  producing 
confusion  in  diagnosis,  431 

opaque  catheter  in,  433 

positions  of  patient  and  ap- 
paratus, 421,  425 

preparation  of  patient,  419 

pyelography  in,  427 

quality  of  the  plate,  426 

quality  of  tube,  425 

sources  of  error  in  diagnosis, 
430 

technique,  420 

time    and    conditions    affect- 
ing, 420 

value  and  importance  of,  419 

variations  in  technique,  421, 
422,   423,   424 
Utensils,  care  of,  127 

Valve  tubes,  96 

Valvular  lesions  in  the  heart 
shadow,  407 

A^elocity  of  x-rays,  17 

A^entilation  of  dark  room,  125 

A'ermiform  appendix,  size  and 
position,  458 

Verrucse,  x-ray  treatment  of, 
475 

Vertical  ray,  218 

Vesical  calculi,  demonstration  of, 
429 

Viewing  screen  for  plates,  118 

Volt,  23 

Voltage,  consumption  and  resist- 
ance, 50 
loss  of,  26 


506 


INDEX 


Voltage,  maintenance  across  tube, 
39 

requirements,  27,  28 
time  relation,  140 
Voltages,    relation    between    pri- 
mary and  secondary,  49 

Warts,  x-ray  treatment  of,  475 

Water  cooling  of  tubes,  31 

Water  rheostat,  93 

Watt,  24 

Wehnelt     interrupter,     operating 

notes,  99 
Winding    ratio    of    transformer, 

49 
Wire  table,  71 


Wiring,  high  tension,  72 

supply  line,  70 
Wrist,  position  for  exposure,  189 

X-ray  transformer,  47 
X-rays,  effects  of,  16 

energy  of,  17 

nature  of,  16 

paths,  17 

production  of,  19 

properties  of,  17,  18 

scattering  of  the,  17 

velocity  of,  17 

Zinc  oxide  ointment  in  radioder- 
matitis,  471,  472 


COLUMBIA  UNIVERSITY 

This  book  is  due  on  the  date  indicated  below,  or  at  the 
expiration  of  a  definite  period  after  the  date  of  borrowing, 
as  provided  by  the  rules  of  the  Library  or  by  special  ar- 
rangement with  the  Librarian  in  charge. 

DATE  BORROWED 

DATE  DUE 

DATE  BORROWED 

DATE  DUE 

'^  1 

C£8^633)M50 

